Source code for spectral_cube.spectral_cube

"""
A class to represent a 3-d position-position-velocity spectral cube.
"""

from __future__ import print_function, absolute_import, division

import warnings
from functools import wraps
import operator
import re
import itertools
import copy
import tempfile
import textwrap
from pathlib import PosixPath
import six
from six.moves import zip, range
import dask.array as da

import astropy.wcs
from astropy import units as u
from astropy.io.fits import PrimaryHDU, BinTableHDU, Header, Card, HDUList
from astropy.utils.console import ProgressBar
from astropy import log
from astropy import wcs
from astropy import convolution
from astropy import stats
from astropy.constants import si
from astropy.io.registry import UnifiedReadWriteMethod

import numpy as np

from radio_beam import Beam, Beams

from . import cube_utils
from . import wcs_utils
from . import spectral_axis
from .masks import (LazyMask, LazyComparisonMask, BooleanArrayMask, MaskBase,
                    is_broadcastable_and_smaller)
from .ytcube import ytCube
from .lower_dimensional_structures import (Projection, Slice, OneDSpectrum,
                                           LowerDimensionalObject,
                                           VaryingResolutionOneDSpectrum
                                          )
from .base_class import (BaseNDClass, SpectralAxisMixinClass,
                         DOPPLER_CONVENTIONS, SpatialCoordMixinClass,
                         MaskableArrayMixinClass, MultiBeamMixinClass,
                         HeaderMixinClass, BeamMixinClass,
                        )
from .utils import (cached, warn_slow, VarianceWarning, BeamWarning,
                    UnsupportedIterationStrategyWarning, WCSMismatchWarning,
                    NotImplementedWarning, SliceWarning, SmoothingWarning,
                    StokesWarning, ExperimentalImplementationWarning,
                    BeamAverageWarning, NonFiniteBeamsWarning, BeamWarning,
                    WCSCelestialError)
from .spectral_axis import (determine_vconv_from_ctype, get_rest_value_from_wcs,
                            doppler_beta, doppler_gamma, doppler_z)
from .io.core import SpectralCubeRead, SpectralCubeWrite

from distutils.version import LooseVersion


__all__ = ['BaseSpectralCube', 'SpectralCube', 'VaryingResolutionSpectralCube']

# apply_everywhere, world: do not have a valid cube to test on
__doctest_skip__ = ['BaseSpectralCube._apply_everywhere']

try:
    from scipy import ndimage
    scipyOK = True
except ImportError:
    scipyOK = False

warnings.filterwarnings('ignore', category=wcs.FITSFixedWarning, append=True)

SIGMA2FWHM = 2. * np.sqrt(2. * np.log(2.))

# convenience structures to keep track of the reversed index
# conventions between WCS and numpy
np2wcs = {2: 0, 1: 1, 0: 2}


_NP_DOC = """
Ignores excluded mask elements.

Parameters
----------
axis : int (optional)
   The axis to collapse, or None to perform a global aggregation
how : cube | slice | ray | auto
   How to compute the aggregation. All strategies give the same
   result, but certain strategies are more efficient depending
   on data size and layout. Cube/slice/ray iterate over
   decreasing subsets of the data, to conserve memory.
   Default='auto'
""".replace('\n', '\n        ')


def aggregation_docstring(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        return func(*args, **kwargs)

    wrapper.__doc__ += _NP_DOC
    return wrapper


_PARALLEL_DOC = """

Other Parameters
----------------
parallel : bool
    Use joblib to parallelize the operation.
    If set to ``False``, will force the use of a single core without
    using ``joblib``.
num_cores : int or None
    The number of cores to use when applying this function in parallel
    across the cube.
use_memmap : bool
    If specified, a memory mapped temporary file on disk will be
    written to rather than storing the intermediate spectra in memory.
"""


def parallel_docstring(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        return func(*args, **kwargs)

    line1 = wrapper.__doc__.split("\n")[1]
    indentation = " "*(len(line1) - len(line1.lstrip()))

    try:
        wrapper.__doc__ += textwrap.indent(_PARALLEL_DOC, indentation)
    except AttributeError:
        # python2.7
        wrapper.__doc__ = textwrap.dedent(wrapper.__doc__) + _PARALLEL_DOC

    return wrapper

def _apply_spectral_function(arguments, outcube, function, **kwargs):
    """
    Helper function to apply a function to a spectrum.
    Needs to be declared toward the top of the code to allow pickling by
    joblib.
    """
    (spec, includemask, ii, jj) = arguments

    if np.any(includemask):
        outcube[:,jj,ii] = function(spec, **kwargs)
    else:
        outcube[:,jj,ii] = spec


def _apply_spatial_function(arguments, outcube, function, **kwargs):
    """
    Helper function to apply a function to an image.
    Needs to be declared toward the top of the code to allow pickling by
    joblib.
    """
    (img, includemask, ii) = arguments

    if np.any(includemask):
        outcube[ii, :, :] = function(img, **kwargs)
    else:
        outcube[ii, :, :] = img


[docs]class BaseSpectralCube(BaseNDClass, MaskableArrayMixinClass, SpectralAxisMixinClass, SpatialCoordMixinClass, HeaderMixinClass): def __init__(self, data, wcs, mask=None, meta=None, fill_value=np.nan, header=None, allow_huge_operations=False, wcs_tolerance=0.0): # Deal with metadata first because it can affect data reading self._meta = meta or {} # must extract unit from data before stripping it if 'BUNIT' in self._meta: self._unit = cube_utils.convert_bunit(self._meta["BUNIT"]) elif hasattr(data, 'unit'): self._unit = data.unit else: self._unit = None # data must not be a quantity when stored in self._data if hasattr(data, 'unit'): # strip the unit so that it can be treated as cube metadata data = data.value # TODO: mask should be oriented? Or should we assume correctly oriented here? self._data, self._wcs = cube_utils._orient(data, wcs) self._wcs_tolerance = wcs_tolerance self._spectral_axis = None self._mask = mask # specifies which elements to Nan/blank/ignore # object or array-like object, given that WCS needs # to be consistent with data? #assert mask._wcs == self._wcs self._fill_value = fill_value self._header = Header() if header is None else header if not isinstance(self._header, Header): raise TypeError("If a header is given, it must be a fits.Header") # We don't pass the spectral unit via the initializer since the user # should be using ``with_spectral_unit`` if they want to set it. # However, we do want to keep track of what units the spectral axis # should be returned in, otherwise astropy's WCS can change the units, # e.g. km/s -> m/s. # This can be overridden with Header below self._spectral_unit = u.Unit(self._wcs.wcs.cunit[2]) # This operation is kind of expensive? header_specaxnum = astropy.wcs.WCS(header).wcs.spec header_specaxunit = spectral_axis.unit_from_header(self._header, spectral_axis_number=header_specaxnum+1) # Allow the original header spectral axis unit to override the default # unit if header_specaxunit is not None: self._spectral_unit = header_specaxunit self._spectral_scale = spectral_axis.wcs_unit_scale(self._spectral_unit) self.allow_huge_operations = allow_huge_operations self._cache = {} @property def _is_huge(self): return cube_utils.is_huge(self) @property def _new_thing_with(self): return self._new_cube_with def _new_cube_with(self, data=None, wcs=None, mask=None, meta=None, fill_value=None, spectral_unit=None, unit=None, wcs_tolerance=None, **kwargs): data = self._data if data is None else data if unit is None and hasattr(data, 'unit'): if data.unit != self.unit: raise u.UnitsError("New data unit '{0}' does not" " match cube unit '{1}'. You can" " override this by specifying the" " `unit` keyword." .format(data.unit, self.unit)) unit = data.unit elif unit is not None: # convert string units to Units if not isinstance(unit, u.Unit): unit = u.Unit(unit) if hasattr(data, 'unit'): if u.Unit(unit) != data.unit: raise u.UnitsError("The specified new cube unit '{0}' " "does not match the input unit '{1}'." .format(unit, data.unit)) else: data = u.Quantity(data, unit=unit, copy=False) elif self._unit is not None: unit = self.unit wcs = self._wcs if wcs is None else wcs mask = self._mask if mask is None else mask if meta is None: meta = {} meta.update(self._meta) if unit is not None: meta['BUNIT'] = unit.to_string(format='FITS') fill_value = self._fill_value if fill_value is None else fill_value spectral_unit = self._spectral_unit if spectral_unit is None else u.Unit(spectral_unit) cube = self.__class__(data=data, wcs=wcs, mask=mask, meta=meta, fill_value=fill_value, header=self._header, allow_huge_operations=self.allow_huge_operations, wcs_tolerance=wcs_tolerance or self._wcs_tolerance, **kwargs) cube._spectral_unit = spectral_unit cube._spectral_scale = spectral_axis.wcs_unit_scale(spectral_unit) return cube read = UnifiedReadWriteMethod(SpectralCubeRead) write = UnifiedReadWriteMethod(SpectralCubeWrite) @property def unit(self): """ The flux unit """ if self._unit: return self._unit else: return u.one @property def shape(self): """ Length of cube along each axis """ return self._data.shape @property def size(self): """ Number of elements in the cube """ return self._data.size @property def base(self): """ The data type 'base' of the cube - useful for, e.g., joblib """ return self._data.base def __len__(self): return self.shape[0] @property def ndim(self): """ Dimensionality of the data """ return self._data.ndim def __repr__(self): s = "{1} with shape={0}".format(self.shape, self.__class__.__name__) if self.unit is u.one: s += ":\n" else: s += " and unit={0}:\n".format(self.unit) s += (" n_x: {0:6d} type_x: {1:8s} unit_x: {2:5s}" " range: {3:12.6f}:{4:12.6f}\n".format(self.shape[2], self.wcs.wcs.ctype[0], self.wcs.wcs.cunit[0], self.longitude_extrema[0], self.longitude_extrema[1],)) s += (" n_y: {0:6d} type_y: {1:8s} unit_y: {2:5s}" " range: {3:12.6f}:{4:12.6f}\n".format(self.shape[1], self.wcs.wcs.ctype[1], self.wcs.wcs.cunit[1], self.latitude_extrema[0], self.latitude_extrema[1], )) s += (" n_s: {0:6d} type_s: {1:8s} unit_s: {2:5s}" " range: {3:12.3f}:{4:12.3f}".format(self.shape[0], self.wcs.wcs.ctype[2], self._spectral_unit, self.spectral_extrema[0], self.spectral_extrema[1], )) return s @property @cached def spectral_extrema(self): _spectral_min = self.spectral_axis.min() _spectral_max = self.spectral_axis.max() return _spectral_min, _spectral_max
[docs] def apply_numpy_function(self, function, fill=np.nan, reduce=True, how='auto', projection=False, unit=None, check_endian=False, progressbar=False, includemask=False, **kwargs): """ Apply a numpy function to the cube Parameters ---------- function : Numpy ufunc A numpy ufunc to apply to the cube fill : float The fill value to use on the data reduce : bool reduce indicates whether this is a reduce-like operation, that can be accumulated one slice at a time. sum/max/min are like this. argmax/argmin/stddev are not how : cube | slice | ray | auto How to compute the moment. All strategies give the same result, but certain strategies are more efficient depending on data size and layout. Cube/slice/ray iterate over decreasing subsets of the data, to conserve memory. Default='auto' projection : bool Return a :class:`~spectral_cube.lower_dimensional_structures.Projection` if the resulting array is 2D or a OneDProjection if the resulting array is 1D and the sum is over both spatial axes? unit : None or `astropy.units.Unit` The unit to include for the output array. For example, `SpectralCube.max` calls ``SpectralCube.apply_numpy_function(np.max, unit=self.unit)``, inheriting the unit from the original cube. However, for other numpy functions, e.g. `numpy.argmax`, the return is an index and therefore unitless. check_endian : bool A flag to check the endianness of the data before applying the function. This is only needed for optimized functions, e.g. those in the `bottleneck <https://pypi.python.org/pypi/Bottleneck>`_ package. progressbar : bool Show a progressbar while iterating over the slices through the cube? kwargs : dict Passed to the numpy function. Returns ------- result : :class:`~spectral_cube.lower_dimensional_structures.Projection` or `~astropy.units.Quantity` or float The result depends on the value of ``axis``, ``projection``, and ``unit``. If ``axis`` is None, the return will be a scalar with or without units. If axis is an integer, the return will be a :class:`~spectral_cube.lower_dimensional_structures.Projection` if ``projection`` is set """ # leave axis in kwargs to avoid overriding numpy defaults, e.g. if the # default is axis=-1, we don't want to force it to be axis=None by # specifying that in the function definition axis = kwargs.get('axis', None) if how == 'auto': strategy = cube_utils.iterator_strategy(self, axis) else: strategy = how out = None log.debug("applying numpy function {0} with strategy {1}" .format(function, strategy)) if strategy == 'slice' and reduce: out = self._reduce_slicewise(function, fill, check_endian, includemask=includemask, progressbar=progressbar, **kwargs) elif how == 'ray': out = self.apply_function(function, **kwargs) elif how not in ['auto', 'cube']: warnings.warn("Cannot use how=%s. Using how=cube" % how, UnsupportedIterationStrategyWarning) if out is None: out = function(self._get_filled_data(fill=fill, check_endian=check_endian), **kwargs) if axis is None: # return is scalar if unit is not None: return u.Quantity(out, unit=unit) else: return out elif projection and reduce: meta = {'collapse_axis': axis} meta.update(self._meta) if hasattr(axis, '__len__') and len(axis) == 2: # if operation is over two spatial dims if set(axis) == set((1,2)): new_wcs = self._wcs.sub([wcs.WCSSUB_SPECTRAL]) header = self._nowcs_header if cube_utils._has_beam(self): bmarg = {'beam': self.beam} elif cube_utils._has_beams(self): bmarg = {'beams': self.unmasked_beams} else: bmarg = {} return self._oned_spectrum(value=out, wcs=new_wcs, copy=False, unit=unit, header=header, meta=meta, spectral_unit=self._spectral_unit, **bmarg ) else: warnings.warn("Averaging over a spatial and a spectral " "dimension cannot produce a Projection " "quantity (no units or WCS are preserved).", SliceWarning ) return out else: new_wcs = wcs_utils.drop_axis(self._wcs, np2wcs[axis]) header = self._nowcs_header return Projection(out, copy=False, wcs=new_wcs, meta=meta, unit=unit, header=header) else: return out
def _reduce_slicewise(self, function, fill, check_endian, includemask=False, progressbar=False, **kwargs): """ Compute a numpy aggregation by grabbing one slice at a time """ ax = kwargs.pop('axis', None) full_reduce = ax is None ax = ax or 0 if isinstance(ax, tuple): assert len(ax) == 2 # we only work with cubes... iterax = [x for x in range(3) if x not in ax][0] else: iterax = ax log.debug("reducing slicewise with axis = {0}".format(ax)) if includemask: planes = self._iter_mask_slices(iterax) else: planes = self._iter_slices(iterax, fill=fill, check_endian=check_endian) result = next(planes) if progressbar: progressbar = ProgressBar(self.shape[iterax]) pbu = progressbar.update else: pbu = lambda: True if isinstance(ax, tuple): # have to make a result a list of itself, since we already "got" # the first plane above result = [function(result, axis=(0,1), **kwargs)] for plane in planes: # apply to axes 0 and 1, because we're fully reducing the plane # to a number if we're applying over two axes result.append(function(plane, axis=(0,1), **kwargs)) pbu() result = np.array(result) else: for plane in planes: # axis = 2 means we're stacking two planes, the previously # computed one and the current one result = function(np.dstack((result, plane)), axis=2, **kwargs) pbu() if full_reduce: result = function(result) return result
[docs] def get_mask_array(self): """ Convert the mask to a boolean numpy array """ return self._mask.include(data=self._data, wcs=self._wcs, wcs_tolerance=self._wcs_tolerance)
def _naxes_dropped(self, view): """ Determine how many axes are being selected given a view. (1,2) -> 2 None -> 3 1 -> 1 2 -> 1 """ if hasattr(view,'__len__'): return len(view) elif view is None: return 3 else: return 1
[docs] @aggregation_docstring @warn_slow def sum(self, axis=None, how='auto', **kwargs): """ Return the sum of the cube, optionally over an axis. """ from .np_compat import allbadtonan projection = self._naxes_dropped(axis) in (1,2) return self.apply_numpy_function(allbadtonan(np.nansum), fill=np.nan, how=how, axis=axis, unit=self.unit, projection=projection, **kwargs)
[docs] @aggregation_docstring @warn_slow def mean(self, axis=None, how='cube', **kwargs): """ Return the mean of the cube, optionally over an axis. """ projection = self._naxes_dropped(axis) in (1,2) if how == 'slice': # two-pass approach: first total the # of points, # then total the value of the points, then divide # (a one-pass approach is possible but requires # more sophisticated bookkeeping) counts = self._count_nonzero_slicewise(axis=axis, progressbar=kwargs.get('progressbar')) ttl = self.apply_numpy_function(np.nansum, fill=np.nan, how=how, axis=axis, unit=None, projection=False, **kwargs) out = ttl / counts if projection: if self._naxes_dropped(axis) == 1: new_wcs = wcs_utils.drop_axis(self._wcs, np2wcs[axis]) meta = {'collapse_axis': axis} meta.update(self._meta) return Projection(out, copy=False, wcs=new_wcs, meta=meta, unit=self.unit, header=self._nowcs_header) elif axis == (1,2): newwcs = self._wcs.sub([wcs.WCSSUB_SPECTRAL]) if cube_utils._has_beam(self): bmarg = {'beam': self.beam} elif cube_utils._has_beams(self): bmarg = {'beams': self.unmasked_beams} else: bmarg = {} return self._oned_spectrum(value=out, wcs=newwcs, copy=False, unit=self.unit, spectral_unit=self._spectral_unit, meta=self.meta, **bmarg ) else: # this is a weird case, but even if projection is # specified, we can't return a Quantity here because of WCS # issues. `apply_numpy_function` already does this # silently, which is unfortunate. warnings.warn("Averaging over a spatial and a spectral " "dimension cannot produce a Projection " "quantity (no units or WCS are preserved).", SliceWarning ) return out else: return out return self.apply_numpy_function(np.nanmean, fill=np.nan, how=how, axis=axis, unit=self.unit, projection=projection, **kwargs)
def _count_nonzero_slicewise(self, axis=None, progressbar=False): """ Count the number of finite pixels along an axis slicewise. This is a helper function for the mean and std deviation slicewise iterators. """ counts = self.apply_numpy_function(np.sum, fill=np.nan, how='slice', axis=axis, unit=None, projection=False, progressbar=progressbar, includemask=True) return counts
[docs] @aggregation_docstring @warn_slow def std(self, axis=None, how='cube', ddof=0, **kwargs): """ Return the standard deviation of the cube, optionally over an axis. Other Parameters ---------------- ddof : int Means Delta Degrees of Freedom. The divisor used in calculations is ``N - ddof``, where ``N`` represents the number of elements. By default ``ddof`` is zero. """ projection = self._naxes_dropped(axis) in (1,2) if how == 'slice': if axis is None: raise NotImplementedError("The overall standard deviation " "cannot be computed in a slicewise " "manner. Please use a " "different strategy.") if hasattr(axis, '__len__') and len(axis) == 2: return self.apply_numpy_function(np.nanstd, axis=axis, how='slice', projection=projection, unit=self.unit, **kwargs) else: counts = self._count_nonzero_slicewise(axis=axis) ttl = self.apply_numpy_function(np.nansum, fill=np.nan, how='slice', axis=axis, unit=None, projection=False, **kwargs) # Equivalent, but with more overhead: # ttl = self.sum(axis=axis, how='slice').value mean = ttl/counts planes = self._iter_slices(axis, fill=np.nan, check_endian=False) result = (next(planes)-mean)**2 for plane in planes: result = np.nansum(np.dstack((result, (plane-mean)**2)), axis=2) out = (result/(counts-ddof))**0.5 if projection: new_wcs = wcs_utils.drop_axis(self._wcs, np2wcs[axis]) meta = {'collapse_axis': axis} meta.update(self._meta) return Projection(out, copy=False, wcs=new_wcs, meta=meta, unit=self.unit, header=self._nowcs_header) else: return out # standard deviation cannot be computed as a trivial step-by-step # process. There IS a one-pass algorithm for std dev, but it is not # implemented, so we must force cube here. We could and should also # implement raywise reduction return self.apply_numpy_function(np.nanstd, fill=np.nan, how=how, axis=axis, unit=self.unit, projection=projection, **kwargs)
[docs] @aggregation_docstring @warn_slow def mad_std(self, axis=None, how='cube', **kwargs): """ Use astropy's mad_std to computer the standard deviation """ if int(astropy.__version__[0]) < 2: raise NotImplementedError("mad_std requires astropy >= 2") projection = self._naxes_dropped(axis) in (1,2) if how == 'ray' and not hasattr(axis, '__len__'): # no need for fill here; masked-out data are simply not included return self.apply_numpy_function(stats.mad_std, axis=axis, how='ray', unit=self.unit, projection=projection, ignore_nan=True, ) elif how == 'slice' and hasattr(axis, '__len__') and len(axis) == 2: return self.apply_numpy_function(stats.mad_std, axis=axis, how='slice', projection=projection, unit=self.unit, fill=np.nan, ignore_nan=True, **kwargs) elif how in ('ray', 'slice'): raise NotImplementedError('Cannot run mad_std slicewise or raywise ' 'unless the dimensionality is also reduced in the same direction.') else: return self.apply_numpy_function(stats.mad_std, fill=np.nan, axis=axis, unit=self.unit, ignore_nan=True, how=how, projection=projection, **kwargs)
[docs] @aggregation_docstring @warn_slow def max(self, axis=None, how='auto', **kwargs): """ Return the maximum data value of the cube, optionally over an axis. """ projection = self._naxes_dropped(axis) in (1,2) return self.apply_numpy_function(np.nanmax, fill=np.nan, how=how, axis=axis, unit=self.unit, projection=projection, **kwargs)
[docs] @aggregation_docstring @warn_slow def min(self, axis=None, how='auto', **kwargs): """ Return the minimum data value of the cube, optionally over an axis. """ projection = self._naxes_dropped(axis) in (1,2) return self.apply_numpy_function(np.nanmin, fill=np.nan, how=how, axis=axis, unit=self.unit, projection=projection, **kwargs)
[docs] @aggregation_docstring @warn_slow def argmax(self, axis=None, how='auto', **kwargs): """ Return the index of the maximum data value. The return value is arbitrary if all pixels along ``axis`` are excluded from the mask. """ return self.apply_numpy_function(np.nanargmax, fill=-np.inf, reduce=False, projection=False, how=how, axis=axis, **kwargs)
[docs] @aggregation_docstring @warn_slow def argmin(self, axis=None, how='auto', **kwargs): """ Return the index of the minimum data value. The return value is arbitrary if all pixels along ``axis`` are excluded from the mask """ return self.apply_numpy_function(np.nanargmin, fill=np.inf, reduce=False, projection=False, how=how, axis=axis, **kwargs)
def _argmaxmin_world(self, axis, method, **kwargs): ''' Return the spatial or spectral index of the maximum or minimum value. Use `argmax_world` and `argmin_world` directly. ''' operation_name = '{}_world'.format(method) if wcs_utils.is_pixel_axis_to_wcs_correlated(self.wcs, axis): raise WCSCelestialError("{} requires the celestial axes" " to be aligned along image axes." .format(operation_name)) if method == 'argmin': arg_pixel_plane = self.argmin(axis=axis, **kwargs) elif method == 'argmax': arg_pixel_plane = self.argmax(axis=axis, **kwargs) else: raise ValueError("`method` must be 'argmin' or 'argmax'") # Convert to WCS coordinates. out = cube_utils.world_take_along_axis(self, arg_pixel_plane, axis) # Compute whether the mask has any valid data along `axis` collapsed_mask = self.mask.include().any(axis=axis) out[~collapsed_mask] = np.NaN # Return a Projection. new_wcs = wcs_utils.drop_axis(self._wcs, np2wcs[axis]) meta = {'collapse_axis': axis} meta.update(self._meta) return Projection(out, copy=False, wcs=new_wcs, meta=meta, unit=out.unit, header=self._nowcs_header)
[docs] @warn_slow def argmax_world(self, axis, **kwargs): ''' Return the spatial or spectral index of the maximum value along a line of sight. Parameters ---------- axis : int The axis to return the peak location along. e.g., `axis=0` will return the value of the spectral axis at the peak value. kwargs : dict Passed to `~SpectralCube.argmax`. ''' return self._argmaxmin_world(axis, 'argmax', **kwargs)
[docs] @warn_slow def argmin_world(self, axis, **kwargs): ''' Return the spatial or spectral index of the minimum value along a line of sight. Parameters ---------- axis : int The axis to return the peak location along. e.g., `axis=0` will return the value of the spectral axis at the peak value. kwargs : dict Passed to `~SpectralCube.argmin`. ''' return self._argmaxmin_world(axis, 'argmin', **kwargs)
[docs] def chunked(self, chunksize=1000): """ Not Implemented. Iterate over chunks of valid data """ raise NotImplementedError()
def _get_flat_shape(self, axis): """ Get the shape of the array after flattening along an axis """ iteraxes = [0, 1, 2] iteraxes.remove(axis) # x,y are defined as first,second dim to iterate over # (not x,y in pixel space...) nx = self.shape[iteraxes[0]] ny = self.shape[iteraxes[1]] return nx, ny @warn_slow def _apply_everywhere(self, function, *args): """ Return a new cube with ``function`` applied to all pixels Private because this doesn't have an obvious and easy-to-use API Examples -------- >>> newcube = cube.apply_everywhere(np.add, 0.5*u.Jy) """ try: test_result = function(np.ones([1,1,1])*self.unit, *args) # First, check that function returns same # of dims? assert test_result.ndim == 3,"Output is not 3-dimensional" except Exception as ex: raise AssertionError("Function could not be applied to a simple " "cube. The error was: {0}".format(ex)) data = function(u.Quantity(self._get_filled_data(fill=self._fill_value), self.unit, copy=False), *args) return self._new_cube_with(data=data, unit=data.unit) @warn_slow def _cube_on_cube_operation(self, function, cube, equivalencies=[], **kwargs): """ Apply an operation between two cubes. Inherits the metadata of the left cube. Parameters ---------- function : function A function to apply to the cubes cube : SpectralCube Another cube to put into the function equivalencies : list A list of astropy equivalencies kwargs : dict Passed to np.testing.assert_almost_equal """ assert cube.shape == self.shape if not self.unit.is_equivalent(cube.unit, equivalencies=equivalencies): raise u.UnitsError("{0} is not equivalent to {1}" .format(self.unit, cube.unit)) if not wcs_utils.check_equality(self.wcs, cube.wcs, warn_missing=True, **kwargs): warnings.warn("Cube WCSs do not match, but their shapes do", WCSMismatchWarning) try: test_result = function(np.ones([1,1,1])*self.unit, np.ones([1,1,1])*self.unit) # First, check that function returns same # of dims? assert test_result.shape == (1,1,1) except Exception as ex: raise AssertionError("Function {1} could not be applied to a " "pair of simple " "cube. The error was: {0}".format(ex, function)) cube = cube.to(self.unit) data = function(self._data, cube._data) try: # multiplication, division, etc. are valid inter-unit operations unit = function(self.unit, cube.unit) except TypeError: # addition, subtraction are not unit = self.unit return self._new_cube_with(data=data, unit=unit)
[docs] def apply_function(self, function, axis=None, weights=None, unit=None, projection=False, progressbar=False, update_function=None, keep_shape=False, **kwargs): """ Apply a function to valid data along the specified axis or to the whole cube, optionally using a weight array that is the same shape (or at least can be sliced in the same way) Parameters ---------- function : function A function that can be applied to a numpy array. Does not need to be nan-aware axis : 1, 2, 3, or None The axis to operate along. If None, the return is scalar. weights : (optional) np.ndarray An array with the same shape (or slicing abilities/results) as the data cube unit : (optional) `~astropy.units.Unit` The unit of the output projection or value. Not all functions should return quantities with units. projection : bool Return a projection if the resulting array is 2D? progressbar : bool Show a progressbar while iterating over the slices/rays through the cube? keep_shape : bool If `True`, the returned object will be the same dimensionality as the cube. update_function : function An alternative tracker for the progress of applying the function to the cube data. If ``progressbar`` is ``True``, this argument is ignored. Returns ------- result : :class:`~spectral_cube.lower_dimensional_structures.Projection` or `~astropy.units.Quantity` or float The result depends on the value of ``axis``, ``projection``, and ``unit``. If ``axis`` is None, the return will be a scalar with or without units. If axis is an integer, the return will be a :class:`~spectral_cube.lower_dimensional_structures.Projection` if ``projection`` is set """ if axis is None: out = function(self.flattened(), **kwargs) if unit is not None: return u.Quantity(out, unit=unit) else: return out if hasattr(axis, '__len__'): raise NotImplementedError("`apply_function` does not support " "function application across multiple " "axes. Try `apply_numpy_function`.") # determine the output array shape nx, ny = self._get_flat_shape(axis) nz = self.shape[axis] if keep_shape else 1 # allocate memory for output array out = np.empty([nz, nx, ny]) * np.nan if progressbar: progressbar = ProgressBar(nx*ny) pbu = progressbar.update elif update_function is not None: pbu = update_function else: pbu = lambda: True # iterate over "lines of sight" through the cube for y, x, slc in self._iter_rays(axis): # acquire the flattened, valid data for the slice data = self.flattened(slc, weights=weights) if len(data) != 0: result = function(data, **kwargs) if hasattr(result, 'value'): # store result in array out[:, y, x] = result.value else: out[:, y, x] = result pbu() if not keep_shape: out = out[0, :, :] if projection and axis in (0, 1, 2): new_wcs = wcs_utils.drop_axis(self._wcs, np2wcs[axis]) meta = {'collapse_axis': axis} meta.update(self._meta) return Projection(out, copy=False, wcs=new_wcs, meta=meta, unit=unit, header=self._nowcs_header) else: return out
def _iter_rays(self, axis=None): """ Iterate over view corresponding to lines-of-sight through a cube along the specified axis """ ny, nx = self._get_flat_shape(axis) for y in range(ny): for x in range(nx): # create length-1 view for each position slc = [slice(y, y + 1), slice(x, x + 1), ] # create a length-N slice (all-inclusive) along the selected axis slc.insert(axis, slice(None)) yield y, x, tuple(slc) def _iter_slices(self, axis, fill=np.nan, check_endian=False): """ Iterate over the cube one slice at a time, replacing masked elements with fill """ view = [slice(None)] * 3 for x in range(self.shape[axis]): view[axis] = x yield self._get_filled_data(view=tuple(view), fill=fill, check_endian=check_endian) def _iter_mask_slices(self, axis): """ Iterate over the cube one slice at a time, replacing masked elements with fill """ view = [slice(None)] * 3 for x in range(self.shape[axis]): view[axis] = x yield self._mask.include(data=self._data, view=tuple(view), wcs=self._wcs, wcs_tolerance=self._wcs_tolerance, )
[docs] def flattened(self, slice=(), weights=None): """ Return a slice of the cube giving only the valid data (i.e., removing bad values) Parameters ---------- slice: 3-tuple A length-3 tuple of view (or any equivalent valid slice of a cube) weights: (optional) np.ndarray An array with the same shape (or slicing abilities/results) as the data cube """ data = self._mask._flattened(data=self._data, wcs=self._wcs, view=slice) if isinstance(data, da.Array): # Quantity does not work well with lazily evaluated data with an # unkonwn shape (which is the case when doing boolean indexing of arrays) data = self._compute(data) if weights is not None: weights = self._mask._flattened(data=weights, wcs=self._wcs, view=slice) return u.Quantity(data * weights, self.unit, copy=False) else: return u.Quantity(data, self.unit, copy=False)
[docs] def median(self, axis=None, iterate_rays=False, **kwargs): """ Compute the median of an array, optionally along an axis. Ignores excluded mask elements. Parameters ---------- axis : int (optional) The axis to collapse iterate_rays : bool Iterate over individual rays? This mode is slower but can save RAM costs, which may be extreme for large cubes Returns ------- med : ndarray The median """ try: from bottleneck import nanmedian bnok = True except ImportError: bnok = False # slicewise median is nonsense, must force how = 'cube' # bottleneck.nanmedian does not allow axis to be a list or tuple if bnok and not iterate_rays and not isinstance(axis, (list, tuple)): log.debug("Using bottleneck nanmedian") result = self.apply_numpy_function(nanmedian, axis=axis, projection=True, unit=self.unit, how='cube', check_endian=True, **kwargs) elif hasattr(np, 'nanmedian') and not iterate_rays: log.debug("Using numpy nanmedian") result = self.apply_numpy_function(np.nanmedian, axis=axis, projection=True, unit=self.unit, how='cube',**kwargs) else: log.debug("Using numpy median iterating over rays") result = self.apply_function(np.median, projection=True, axis=axis, unit=self.unit, **kwargs) return result
[docs] def percentile(self, q, axis=None, iterate_rays=False, **kwargs): """ Return percentiles of the data. Parameters ---------- q : float The percentile to compute axis : int, or None Which axis to compute percentiles over iterate_rays : bool Iterate over individual rays? This mode is slower but can save RAM costs, which may be extreme for large cubes """ if hasattr(np, 'nanpercentile') and not iterate_rays: result = self.apply_numpy_function(np.nanpercentile, q=q, axis=axis, projection=True, unit=self.unit, how='cube', **kwargs) else: result = self.apply_function(np.percentile, q=q, axis=axis, projection=True, unit=self.unit, **kwargs) return result
[docs] def with_mask(self, mask, inherit_mask=True, wcs_tolerance=None): """ Return a new SpectralCube instance that contains a composite mask of the current SpectralCube and the new ``mask``. Values of the mask that are ``True`` will be *included* (masks are analogous to numpy boolean index arrays, they are the inverse of the ``.mask`` attribute of a numpy masked array). Parameters ---------- mask : :class:`~spectral_cube.masks.MaskBase` instance, or boolean numpy array The mask to apply. If a boolean array is supplied, it will be converted into a mask, assuming that `True` values indicate included elements. inherit_mask : bool (optional, default=True) If True, combines the provided mask with the mask currently attached to the cube wcs_tolerance : None or float The tolerance of difference in WCS parameters between the cube and the mask. Defaults to `self._wcs_tolerance` (which itself defaults to 0.0) if unspecified Returns ------- new_cube : :class:`SpectralCube` A cube with the new mask applied. Notes ----- This operation returns a view into the data, and not a copy. """ if isinstance(mask, np.ndarray): if not is_broadcastable_and_smaller(mask.shape, self._data.shape): raise ValueError("Mask shape is not broadcastable to data shape: " "%s vs %s" % (mask.shape, self._data.shape)) mask = BooleanArrayMask(mask, self._wcs, shape=self._data.shape) if self._mask is not None and inherit_mask: new_mask = np.bitwise_and(self._mask, mask) else: new_mask = mask new_mask._validate_wcs(new_data=self._data, new_wcs=self._wcs, wcs_tolerance=wcs_tolerance or self._wcs_tolerance) return self._new_cube_with(mask=new_mask, wcs_tolerance=wcs_tolerance)
def __getitem__(self, view): # Need to allow self[:], self[:,:] if isinstance(view, (slice,int,np.int64)): view = (view, slice(None), slice(None)) elif len(view) == 2: view = view + (slice(None),) elif len(view) > 3: raise IndexError("Too many indices") meta = {} meta.update(self._meta) slice_data = [(s.start, s.stop, s.step) if hasattr(s,'start') else s for s in view] if 'slice' in meta: meta['slice'].append(slice_data) else: meta['slice'] = [slice_data] intslices = [2-ii for ii,s in enumerate(view) if not hasattr(s,'start')] if intslices: if len(intslices) > 1: if 2 in intslices: raise NotImplementedError("1D slices along non-spectral " "axes are not yet implemented.") newwcs = self._wcs.sub([a for a in (1,2,3) if a not in [x+1 for x in intslices]]) if cube_utils._has_beam(self): bmarg = {'beam': self.beam} elif cube_utils._has_beams(self): bmarg = {'beams': self.beams} else: bmarg = {} return self._oned_spectrum(value=self._data[view], wcs=newwcs, copy=False, unit=self.unit, spectral_unit=self._spectral_unit, mask=self.mask[view] if self.mask is not None else None, meta=meta, **bmarg ) # only one element, so drop an axis newwcs = wcs_utils.drop_axis(self._wcs, intslices[0]) header = self._nowcs_header if intslices[0] == 0: # celestial: can report the wavelength/frequency of the axis header['CRVAL3'] = self.spectral_axis[intslices[0]].value header['CDELT3'] = self.wcs.sub([wcs.WCSSUB_SPECTRAL]).wcs.cdelt[0] header['CUNIT3'] = self._spectral_unit.to_string(format='FITS') return Slice(value=self.filled_data[view], mask=self.mask[view] if self.mask is not None else None, wcs=newwcs, copy=False, unit=self.unit, header=header, meta=meta) newmask = self._mask[view] if self._mask is not None else None newwcs = wcs_utils.slice_wcs(self._wcs, view, shape=self.shape) return self._new_cube_with(data=self._data[view], wcs=newwcs, mask=newmask, meta=meta) @property def unitless(self): """Return a copy of self with unit set to None""" newcube = self._new_cube_with() newcube._unit = None return newcube
[docs] def with_spectral_unit(self, unit, velocity_convention=None, rest_value=None): """ Returns a new Cube with a different Spectral Axis unit Parameters ---------- unit : :class:`~astropy.units.Unit` Any valid spectral unit: velocity, (wave)length, or frequency. Only vacuum units are supported. velocity_convention : 'relativistic', 'radio', or 'optical' The velocity convention to use for the output velocity axis. Required if the output type is velocity. This can be either one of the above strings, or an `astropy.units` equivalency. rest_value : :class:`~astropy.units.Quantity` A rest wavelength or frequency with appropriate units. Required if output type is velocity. The cube's WCS should include this already if the *input* type is velocity, but the WCS's rest wavelength/frequency can be overridden with this parameter. .. note: This must be the rest frequency/wavelength *in vacuum*, even if your cube has air wavelength units """ newwcs,newmeta = self._new_spectral_wcs(unit=unit, velocity_convention=velocity_convention, rest_value=rest_value) if self._mask is not None: newmask = self._mask.with_spectral_unit(unit, velocity_convention=velocity_convention, rest_value=rest_value) newmask._wcs = newwcs else: newmask = None cube = self._new_cube_with(wcs=newwcs, mask=newmask, meta=newmeta, spectral_unit=unit) return cube
@cube_utils.slice_syntax def unmasked_data(self, view): """ Return a view of the subset of the underlying data, ignoring the mask. Returns ------- data : Quantity instance The unmasked data """ values = self._data[view] # Astropy Quantities don't play well with dask arrays with shape () if isinstance(values, da.Array) and values.shape == (): values = values.compute() return u.Quantity(values, self.unit, copy=False)
[docs] def unmasked_copy(self): """ Return a copy of the cube with no mask (i.e., all data included) """ newcube = self._new_cube_with() newcube._mask = None return newcube
@cached def _pix_cen(self): """ Offset of every pixel from the origin, along each direction Returns ------- tuple of spectral_offset, y_offset, x_offset, each 3D arrays describing the distance from the origin Notes ----- These arrays are broadcast, and are not memory intensive Each array is in the units of the corresponding wcs.cunit, but this is implicit (e.g., they are not astropy Quantity arrays) """ # Start off by extracting the world coordinates of the pixels _, lat, lon = self.world[0, :, :] spectral, _, _ = self.world[:, 0, 0] spectral -= spectral[0] # offset from first pixel # Convert to radians lon = np.radians(lon) lat = np.radians(lat) # Find the dx and dy arrays from astropy.coordinates.angle_utilities import angular_separation dx = angular_separation(lon[:, :-1], lat[:, :-1], lon[:, 1:], lat[:, :-1]) dy = angular_separation(lon[:-1, :], lat[:-1, :], lon[1:, :], lat[1:, :]) # Find the cumulative offset - need to add a zero at the start x = np.zeros(self._data.shape[1:]) y = np.zeros(self._data.shape[1:]) x[:, 1:] = np.cumsum(np.degrees(dx), axis=1) y[1:, :] = np.cumsum(np.degrees(dy), axis=0) if isinstance(self._data, da.Array): x, y, spectral = da.broadcast_arrays(x[None,:,:], y[None,:,:], spectral[:,None,None]) # NOTE: we need to rechunk these to the actual data size, otherwise # the resulting arrays have a single chunk which can cause issues with # da.store (which writes data out in chunks) return (spectral.rechunk(self._data.chunksize), y.rechunk(self._data.chunksize), x.rechunk(self._data.chunksize)) else: x, y, spectral = np.broadcast_arrays(x[None,:,:], y[None,:,:], spectral[:,None,None]) return spectral, y, x @cached def _pix_size_slice(self, axis): """ Return the size of each pixel along any given direction. Assumes pixels have equal size. Also assumes that the spectral and spatial directions are separable, which is enforced throughout this code. Parameters ---------- axis : 0, 1, or 2 The axis along which to compute the pixel size Returns ------- Pixel size in units of either degrees or the appropriate spectral unit """ if axis == 0: # note that self._spectral_scale is required here because wcs # forces into units of m, m/s, or Hz return np.abs(self.wcs.pixel_scale_matrix[2,2]) * self._spectral_scale elif axis in (1,2): # the pixel size is a projection. I think the pixel_scale_matrix # must be symmetric, such that psm[axis,:]**2 == psm[:,axis]**2 return np.sum(self.wcs.pixel_scale_matrix[2-axis,:]**2)**0.5 else: raise ValueError("Cubes have 3 axes.") @cached def _pix_size(self): """ Return the size of each pixel along each direction, in world units Returns ------- dv, dy, dx : tuple of 3D arrays The extent of each pixel along each direction Notes ----- These arrays are broadcast, and are not memory intensive Each array is in the units of the corresponding wcs.cunit, but this is implicit (e.g., they are not astropy Quantity arrays) """ # First, scale along x direction xpix = np.linspace(-0.5, self._data.shape[2] - 0.5, self._data.shape[2] + 1) ypix = np.linspace(0., self._data.shape[1] - 1, self._data.shape[1]) xpix, ypix = np.meshgrid(xpix, ypix) zpix = np.zeros(xpix.shape) lon, lat, _ = self._wcs.all_pix2world(xpix, ypix, zpix, 0) # Convert to radians lon = np.radians(lon) lat = np.radians(lat) # Find the dx and dy arrays from astropy.coordinates.angle_utilities import angular_separation dx = angular_separation(lon[:, :-1], lat[:, :-1], lon[:, 1:], lat[:, :-1]) # Next, scale along y direction xpix = np.linspace(0., self._data.shape[2] - 1, self._data.shape[2]) ypix = np.linspace(-0.5, self._data.shape[1] - 0.5, self._data.shape[1] + 1) xpix, ypix = np.meshgrid(xpix, ypix) zpix = np.zeros(xpix.shape) lon, lat, _ = self._wcs.all_pix2world(xpix, ypix, zpix, 0) # Convert to radians lon = np.radians(lon) lat = np.radians(lat) # Find the dx and dy arrays from astropy.coordinates.angle_utilities import angular_separation dy = angular_separation(lon[:-1, :], lat[:-1, :], lon[1:, :], lat[1:, :]) # Next, spectral coordinates zpix = np.linspace(-0.5, self._data.shape[0] - 0.5, self._data.shape[0] + 1) xpix = np.zeros(zpix.shape) ypix = np.zeros(zpix.shape) _, _, spectral = self._wcs.all_pix2world(xpix, ypix, zpix, 0) # Take spectral units into account # order of operations here is crucial! If this is done after # broadcasting, the full array size is allocated, which is bad! dspectral = np.diff(spectral) * self._spectral_scale dx = np.abs(np.degrees(dx.reshape(1, dx.shape[0], dx.shape[1]))) dy = np.abs(np.degrees(dy.reshape(1, dy.shape[0], dy.shape[1]))) dspectral = np.abs(dspectral.reshape(-1, 1, 1)) dx, dy, dspectral = np.broadcast_arrays(dx, dy, dspectral) return dspectral, dy, dx
[docs] def moment(self, order=0, axis=0, how='auto'): """ Compute moments along the spectral axis. Moments are defined as follows, where :math:`I` is the intensity in a channel and :math:`x` is the spectral coordinate: Moment 0: .. math:: M_0 \\int I dx Moment 1: .. math:: M_1 = \\frac{\\int I x dx}{M_0} Moment N: .. math:: M_N = \\frac{\\int I (x - M_1)^N dx}{M_0} .. warning:: Note that these follow the mathematical definitions of moments, and therefore the second moment will return a variance map. To get linewidth maps, you can instead use the :meth:`~SpectralCube.linewidth_fwhm` or :meth:`~SpectralCube.linewidth_sigma` methods. Parameters ---------- order : int The order of the moment to take. Default=0 axis : int The axis along which to compute the moment. Default=0 how : cube | slice | ray | auto How to compute the moment. All strategies give the same result, but certain strategies are more efficient depending on data size and layout. Cube/slice/ray iterate over decreasing subsets of the data, to conserve memory. Default='auto' Returns ------- map [, wcs] The moment map (numpy array) and, if wcs=True, the WCS object describing the map Notes ----- Generally, how='cube' is fastest for small cubes that easily fit into memory. how='slice' is best for most larger datasets. how='ray' is probably only a good idea for very large cubes whose data are contiguous over the axis of the moment map. For the first moment, the result for axis=1, 2 is the angular offset *relative to the cube face*. For axis=0, it is the *absolute* velocity/frequency of the first moment. """ if axis == 0 and order == 2: warnings.warn("Note that the second moment returned will be a " "variance map. To get a linewidth map, use the " "SpectralCube.linewidth_fwhm() or " "SpectralCube.linewidth_sigma() methods instead.", VarianceWarning) from ._moments import (moment_slicewise, moment_cubewise, moment_raywise, moment_auto) dispatch = dict(slice=moment_slicewise, cube=moment_cubewise, ray=moment_raywise, auto=moment_auto) if how not in dispatch: return ValueError("Invalid how. Must be in %s" % sorted(list(dispatch.keys()))) out = dispatch[how](self, order, axis) # apply units if order == 0: if axis == 0 and self._spectral_unit is not None: axunit = unit = self._spectral_unit else: axunit = unit = u.Unit(self._wcs.wcs.cunit[np2wcs[axis]]) out = u.Quantity(out, self.unit * axunit, copy=False) else: if axis == 0 and self._spectral_unit is not None: unit = self._spectral_unit ** max(order, 1) else: unit = u.Unit(self._wcs.wcs.cunit[np2wcs[axis]]) ** max(order, 1) out = u.Quantity(out, unit, copy=False) # special case: for order=1, axis=0, you usually want # the absolute velocity and not the offset if order == 1 and axis == 0: out += self.world[0, :, :][0] new_wcs = wcs_utils.drop_axis(self._wcs, np2wcs[axis]) meta = {'moment_order': order, 'moment_axis': axis, 'moment_method': how} meta.update(self._meta) return Projection(out, copy=False, wcs=new_wcs, meta=meta, header=self._nowcs_header)
[docs] def moment0(self, axis=0, how='auto'): """ Compute the zeroth moment along an axis. See :meth:`moment`. """ return self.moment(axis=axis, order=0, how=how)
[docs] def moment1(self, axis=0, how='auto'): """ Compute the 1st moment along an axis. For an explanation of the ``axis`` and ``how`` parameters, see :meth:`moment`. """ return self.moment(axis=axis, order=1, how=how)
[docs] def moment2(self, axis=0, how='auto'): """ Compute the 2nd moment along an axis. For an explanation of the ``axis`` and ``how`` parameters, see :meth:`moment`. """ return self.moment(axis=axis, order=2, how=how)
[docs] def linewidth_sigma(self, how='auto'): """ Compute a (sigma) linewidth map along the spectral axis. For an explanation of the ``how`` parameter, see :meth:`moment`. """ with np.errstate(invalid='ignore'): with warnings.catch_warnings(): warnings.simplefilter("ignore", VarianceWarning) return np.sqrt(self.moment2(how=how))
[docs] def linewidth_fwhm(self, how='auto'): """ Compute a (FWHM) linewidth map along the spectral axis. For an explanation of the ``how`` parameter, see :meth:`moment`. """ return self.linewidth_sigma() * SIGMA2FWHM
@property def spectral_axis(self): """ A `~astropy.units.Quantity` array containing the central values of each channel along the spectral axis. """ return self.world[:, 0, 0][0].ravel() @property def velocity_convention(self): """ The `~astropy.units.equivalencies` that describes the spectral axis """ return spectral_axis.determine_vconv_from_ctype(self.wcs.wcs.ctype[self.wcs.wcs.spec])
[docs] def closest_spectral_channel(self, value): """ Find the index of the closest spectral channel to the specified spectral coordinate. Parameters ---------- value : :class:`~astropy.units.Quantity` The value of the spectral coordinate to search for. """ # TODO: we have to not compute this every time spectral_axis = self.spectral_axis try: value = value.to(spectral_axis.unit, equivalencies=u.spectral()) except u.UnitsError: if value.unit.is_equivalent(u.Hz, equivalencies=u.spectral()): if spectral_axis.unit.is_equivalent(u.m / u.s): raise u.UnitsError("Spectral axis is in velocity units and " "'value' is in frequency-equivalent units " "- use SpectralCube.with_spectral_unit " "first to convert the cube to frequency-" "equivalent units, or search for a " "velocity instead") else: raise u.UnitsError("Unexpected spectral axis units: {0}".format(spectral_axis.unit)) elif value.unit.is_equivalent(u.m / u.s): if spectral_axis.unit.is_equivalent(u.Hz, equivalencies=u.spectral()): raise u.UnitsError("Spectral axis is in frequency-equivalent " "units and 'value' is in velocity units " "- use SpectralCube.with_spectral_unit " "first to convert the cube to frequency-" "equivalent units, or search for a " "velocity instead") else: raise u.UnitsError("Unexpected spectral axis units: {0}".format(spectral_axis.unit)) else: raise u.UnitsError("'value' should be in frequency equivalent or velocity units (got {0})".format(value.unit)) # TODO: optimize the next line - just brute force for now return np.argmin(np.abs(spectral_axis - value))
[docs] def spectral_slab(self, lo, hi): """ Extract a new cube between two spectral coordinates Parameters ---------- lo, hi : :class:`~astropy.units.Quantity` The lower and upper spectral coordinate for the slab range. The units should be compatible with the units of the spectral axis. If the spectral axis is in frequency-equivalent units and you want to select a range in velocity, or vice-versa, you should first use :meth:`~spectral_cube.SpectralCube.with_spectral_unit` to convert the units of the spectral axis. """ # Find range of values for spectral axis ilo = self.closest_spectral_channel(lo) ihi = self.closest_spectral_channel(hi) if ilo > ihi: ilo, ihi = ihi, ilo ihi += 1 # Create WCS slab wcs_slab = self._wcs.deepcopy() wcs_slab.wcs.crpix[2] -= ilo # Create mask slab if self._mask is None: mask_slab = None else: try: mask_slab = self._mask[ilo:ihi, :, :] except NotImplementedError: warnings.warn("Mask slicing not implemented for " "{0} - dropping mask". format(self._mask.__class__.__name__), NotImplementedWarning ) mask_slab = None # Create new spectral cube slab = self._new_cube_with(data=self._data[ilo:ihi], wcs=wcs_slab, mask=mask_slab) # TODO: we could change the WCS to give a spectral axis in the # correct units as requested - so if the initial cube is in Hz and we # request a range in km/s, we could adjust the WCS to be in km/s # instead return slab
[docs] def minimal_subcube(self, spatial_only=False): """ Return the minimum enclosing subcube where the mask is valid Parameters ---------- spatial_only: bool Only compute the minimal subcube in the spatial dimensions """ if self._mask is not None: return self[self.subcube_slices_from_mask(self._mask, spatial_only=spatial_only)] else: return self[:]
[docs] def subcube_from_mask(self, region_mask): """ Given a mask, return the minimal subcube that encloses the mask Parameters ---------- region_mask: `~spectral_cube.masks.MaskBase` or boolean `numpy.ndarray` The mask with appropraite WCS or an ndarray with matched coordinates """ return self[self.subcube_slices_from_mask(region_mask)]
[docs] def subcube_slices_from_mask(self, region_mask, spatial_only=False): """ Given a mask, return the slices corresponding to the minimum subcube that encloses the mask Parameters ---------- region_mask: `~spectral_cube.masks.MaskBase` or boolean `numpy.ndarray` The mask with appropriate WCS or an ndarray with matched coordinates spatial_only: bool Return only slices that affect the spatial dimensions; the spectral dimension will be left unchanged """ if not scipyOK: raise ImportError("Scipy could not be imported: this function won't work.") if isinstance(region_mask, np.ndarray): if is_broadcastable_and_smaller(region_mask.shape, self.shape): region_mask = BooleanArrayMask(region_mask, self._wcs) else: raise ValueError("Mask shape does not match cube shape.") include = region_mask.include(self._data, self._wcs, wcs_tolerance=self._wcs_tolerance) if not include.any(): return (slice(0),)*3 slices = ndimage.find_objects(np.broadcast_arrays(include, self._data)[0])[0] if spatial_only: slices = (slice(None), slices[1], slices[2]) return tuple(slices)
[docs] def subcube(self, xlo='min', xhi='max', ylo='min', yhi='max', zlo='min', zhi='max', rest_value=None): """ Extract a sub-cube spatially and spectrally. When spatial WCS dimensions are given as an `~astropy.units.Quantity`, the spatial coordinates of the 'lo' and 'hi' corners are solved together. This minimizes WCS variations due to the sky curvature when slicing from a large (>1 deg) image. Parameters ---------- [xyz]lo/[xyz]hi : int or :class:`~astropy.units.Quantity` or ``min``/``max`` The endpoints to extract. If given as a quantity, will be interpreted as World coordinates. If given as a string or int, will be interpreted as pixel coordinates. """ dims = {'x': 2, 'y': 1, 'z': 0} limit_dict = {} limit_dict['zlo'] = 0 if zlo == 'min' else zlo limit_dict['zhi'] = self.shape[0] if zhi == 'max' else zhi # Specific warning for slicing a frequency axis with a velocity or # vice/versa if ((hasattr(zlo, 'unit') and not zlo.unit.is_equivalent(self.spectral_axis.unit)) or (hasattr(zhi, 'unit') and not zhi.unit.is_equivalent(self.spectral_axis.unit))): raise u.UnitsError("Spectral units are not equivalent to the " "spectral slice. Use `.with_spectral_unit` " "to convert to equivalent units first") # Solve for the spatial pixel indices together limit_dict_spat = wcs_utils.find_spatial_pixel_index(self, xlo, xhi, ylo, yhi) limit_dict.update(limit_dict_spat) # Handle the z (spectral) axis. This shouldn't change # much spacially, so solve one at a time # Track if the z axis values had units. Will need to make a +1 correction below united = [] for lim in limit_dict: if 'z' not in lim: continue limval = limit_dict[lim] if hasattr(limval, 'unit'): united.append(lim) dim = dims[lim[0]] sl = [slice(0,1)]*2 sl.insert(dim, slice(None)) sl = tuple(sl) spine = self.world[sl][dim] val = np.argmin(np.abs(limval-spine)) if limval > spine.max() or limval < spine.min(): log.warning("The limit {0} is out of bounds." " Using min/max instead.".format(lim)) limit_dict[lim] = val # Check spectral axis ordering. hi,lo = limit_dict['zhi'], limit_dict['zlo'] if hi < lo: # must have high > low limit_dict['zhi'], limit_dict['zlo'] = lo, hi if 'zhi' in united: # End-inclusive indexing: need to add one for the high slice # Only do this for converted values, not for pixel values # (i.e., if the xlo/ylo/zlo value had units) limit_dict['zhi'] += 1 for xx in 'zyx': if limit_dict[xx+'hi'] == limit_dict[xx+'lo']: # I think this should be unreachable now raise ValueError("The slice in the {0} direction will remove " "all elements. If you want a single-channel " "slice, you need a different approach." .format(xx)) slices = [slice(limit_dict[xx+'lo'], limit_dict[xx+'hi']) for xx in 'zyx'] slices = tuple(slices) log.debug('slices: {0}'.format(slices)) return self[slices]
[docs] def subcube_from_ds9region(self, ds9_region, allow_empty=False): """ Extract a masked subcube from a ds9 region (only functions on celestial dimensions) Parameters ---------- ds9_region: str The DS9 region(s) to extract allow_empty: bool If this is False, an exception will be raised if the region contains no overlap with the cube """ import regions if isinstance(ds9_region, six.string_types): region_list = regions.DS9Parser(ds9_region).shapes.to_regions() else: raise TypeError("{0} should be a DS9 string".format(ds9_region)) return self.subcube_from_regions(region_list, allow_empty)
[docs] def subcube_from_crtfregion(self, crtf_region, allow_empty=False): """ Extract a masked subcube from a CRTF region. Parameters ---------- crtf_region: str The CRTF region(s) string to extract allow_empty: bool If this is False, an exception will be raised if the region contains no overlap with the cube """ import regions if isinstance(crtf_region, six.string_types): region_list = regions.CRTFParser(crtf_region).shapes.to_regions() else: raise TypeError("{0} should be a CRTF string".format(crtf_region)) return self.subcube_from_regions(region_list, allow_empty)
[docs] def subcube_from_regions(self, region_list, allow_empty=False): """ Extract a masked subcube from a list of ``regions.Region`` object (only functions on celestial dimensions) Parameters ---------- region_list: ``regions.Region`` list The region(s) to extract allow_empty: bool, optional If this is False, an exception will be raised if the region contains no overlap with the cube. Default is False. """ import regions # Convert every region to a `regions.PixelRegion` object. regs = [] for x in region_list: if isinstance(x, regions.SkyRegion): regs.append(x.to_pixel(self.wcs.celestial)) elif isinstance(x, regions.PixelRegion): regs.append(x) else: raise TypeError("'{}' should be `regions.Region` object".format(x)) # List of regions are converted to a `regions.CompoundPixelRegion` object. compound_region = _regionlist_to_single_region(regs) # Compound mask of all the regions. mask = compound_region.to_mask() # Collecting frequency/velocity range, velocity type and rest frequency # of each region. ranges = [x.meta.get('range', None) for x in regs] veltypes = [x.meta.get('veltype', None) for x in regs] restfreqs = [x.meta.get('restfreq', None) for x in regs] xlo, xhi, ylo, yhi = mask.bbox.ixmin, mask.bbox.ixmax, mask.bbox.iymin, mask.bbox.iymax # Negative indices will do bad things, like wrap around the cube # If xhi/yhi are negative, there is not overlap if (xhi < 0) or (yhi < 0): raise ValueError("Region is outside of cube.") if xlo < 0: xlo = 0 if ylo < 0: ylo = 0 # If None, then the whole spectral range of the cube is selected. if None in ranges: subcube = self.subcube(xlo=xlo, ylo=ylo, xhi=xhi, yhi=yhi) else: ranges = self._velocity_freq_conversion_regions(ranges, veltypes, restfreqs) zlo = min([x[0] for x in ranges]) zhi = max([x[1] for x in ranges]) slab = self.spectral_slab(zlo, zhi) subcube = slab.subcube(xlo=xlo, ylo=ylo, xhi=xhi, yhi=yhi) if any(dim == 0 for dim in subcube.shape): if allow_empty: warnings.warn("The derived subset is empty: the region does not" " overlap with the cube (but allow_empty=True).") else: raise ValueError("The derived subset is empty: the region does not" " overlap with the cube.") # cropping the mask from top left corner so that it fits the subcube. maskarray = mask.data[:subcube.shape[1], :subcube.shape[2]].astype('bool') masked_subcube = subcube.with_mask(BooleanArrayMask(maskarray, subcube.wcs, shape=subcube.shape)) # by using ceil / floor above, we potentially introduced a NaN buffer # that we can now crop out return masked_subcube.minimal_subcube(spatial_only=True)
def _velocity_freq_conversion_regions(self, ranges, veltypes, restfreqs): """ Makes the spectral range of the regions compatible with the spectral convention of the cube. ranges: `~astropy.units.Quantity` object List of range(a list of max and min limits on the spectral axis) of each ``regions.Region`` object. veltypes: List of `str` It contains list of velocity convention that each region is following. The string should be a combination of the following elements: {'RADIO' | 'OPTICAL' | 'Z' | 'BETA' | 'GAMMA' | 'RELATIVISTIC' | None} An element can be `None` if veltype of the region is unknown and is assumed to take that of the cube. restfreqs: List of `~astropy.units.Quantity` It contains the rest frequency of each region. """ header = self.wcs.to_header() # Obtaining rest frequency of the cube in GHz. restfreq_cube = get_rest_value_from_wcs(self.wcs).to("GHz", equivalencies=u.spectral()) CTYPE3 = header['CTYPE3'] veltype_cube = determine_vconv_from_ctype(CTYPE3) veltype_equivalencies = dict(RADIO=u.doppler_radio, OPTICAL=u.doppler_optical, Z=doppler_z, BETA=doppler_beta, GAMMA=doppler_gamma, RELATIVISTIC=u.doppler_relativistic ) final_ranges = [] for range, veltype, restfreq in zip(ranges, veltypes, restfreqs): if restfreq is None: restfreq = restfreq_cube restfreq = restfreq.to("GHz", equivalencies=u.spectral()) if veltype not in veltype_equivalencies and veltype is not None: raise ValueError("Spectral Cube doesn't support {} this type of" "velocity".format(veltype)) veltype = veltype_equivalencies.get(veltype, veltype_cube) # Because there is chance that the veltype and rest frequency # of the region may not be the same as that of cube, we convert it # to frequency and then convert to the spectral unit of the cube. freq_range = (u.Quantity(range).to("GHz", equivalencies=veltype(restfreq))) final_ranges.append(freq_range.to(header['CUNIT3'], equivalencies=veltype_cube(restfreq_cube))) return final_ranges def _val_to_own_unit(self, value, operation='compare', tofrom='to', keepunit=False): """ Given a value, check if it has a unit. If it does, convert to the cube's unit. If it doesn't, raise an exception. """ if isinstance(value, SpectralCube): if self.unit.is_equivalent(value.unit): return value else: return value.to(self.unit) elif hasattr(value, 'unit'): if keepunit: return value.to(self.unit) else: return value.to(self.unit).value else: raise ValueError("Can only {operation} cube objects {tofrom}" " SpectralCubes or Quantities with " "a unit attribute." .format(operation=operation, tofrom=tofrom)) def __gt__(self, value): """ Return a LazyMask representing the inequality Parameters ---------- value : number The threshold """ value = self._val_to_own_unit(value) return LazyComparisonMask(operator.gt, value, data=self._data, wcs=self._wcs) def __ge__(self, value): value = self._val_to_own_unit(value) return LazyComparisonMask(operator.ge, value, data=self._data, wcs=self._wcs) def __le__(self, value): value = self._val_to_own_unit(value) return LazyComparisonMask(operator.le, value, data=self._data, wcs=self._wcs) def __lt__(self, value): value = self._val_to_own_unit(value) return LazyComparisonMask(operator.lt, value, data=self._data, wcs=self._wcs) def __eq__(self, value): value = self._val_to_own_unit(value) return LazyComparisonMask(operator.eq, value, data=self._data, wcs=self._wcs) def __hash__(self): return id(self) def __ne__(self, value): value = self._val_to_own_unit(value) return LazyComparisonMask(operator.ne, value, data=self._data, wcs=self._wcs) def __add__(self, value): if isinstance(value, SpectralCube): return self._cube_on_cube_operation(operator.add, value) else: value = self._val_to_own_unit(value, operation='add', tofrom='from', keepunit=True) return self._apply_everywhere(operator.add, value) def __sub__(self, value): if isinstance(value, SpectralCube): return self._cube_on_cube_operation(operator.sub, value) else: value = self._val_to_own_unit(value, operation='subtract', tofrom='from', keepunit=True) return self._apply_everywhere(operator.sub, value) def __mul__(self, value): if isinstance(value, SpectralCube): return self._cube_on_cube_operation(operator.mul, value) else: return self._apply_everywhere(operator.mul, value) def __truediv__(self, value): return self.__div__(value) def __div__(self, value): if isinstance(value, SpectralCube): return self._cube_on_cube_operation(operator.truediv, value) else: return self._apply_everywhere(operator.truediv, value) def __pow__(self, value): if isinstance(value, SpectralCube): return self._cube_on_cube_operation(operator.pow, value) else: return self._apply_everywhere(operator.pow, value)
[docs] def to_yt(self, spectral_factor=1.0, nprocs=None, **kwargs): """ Convert a spectral cube to a yt object that can be further analyzed in yt. Parameters ---------- spectral_factor : float, optional Factor by which to stretch the spectral axis. If set to 1, one pixel in spectral coordinates is equivalent to one pixel in spatial coordinates. If using yt 3.0 or later, additional keyword arguments will be passed onto yt's ``FITSDataset`` constructor. See the yt documentation (http://yt-project.org/docs/3.0/examining/loading_data.html?#fits-data) for details on options for reading FITS data. """ import yt if (('dev' in yt.__version__) or (LooseVersion(yt.__version__) >= LooseVersion('3.0'))): # yt has updated their FITS data set so that only the SpectralCube # variant takes spectral_factor try: from yt.frontends.fits.api import SpectralCubeFITSDataset as FITSDataset except ImportError: from yt.frontends.fits.api import FITSDataset from yt.units.unit_object import UnitParseError data = self._get_filled_data(fill=0.) if isinstance(data, da.Array): # Note that >f8 can cause issues with yt, and for visualization # we don't really need the full 64-bit of floating point # precision, so we cast to float32. data = data.astype(np.float32).compute() hdu = PrimaryHDU(data, header=self.wcs.to_header()) units = str(self.unit.to_string()) hdu.header["BUNIT"] = units hdu.header["BTYPE"] = "flux" ds = FITSDataset(hdu, nprocs=nprocs, spectral_factor=spectral_factor, **kwargs) # Check to make sure the units are legit try: ds.quan(1.0,units) except UnitParseError: raise RuntimeError("The unit %s was not parsed by yt. " % units+ "Check to make sure it is correct.") else: from yt.mods import load_uniform_grid data = {'flux': self._get_filled_data(fill=0.).transpose()} nz, ny, nx = self.shape if nprocs is None: nprocs = 1 bbox = np.array([[0.5,float(nx)+0.5], [0.5,float(ny)+0.5], [0.5,spectral_factor*float(nz)+0.5]]) ds = load_uniform_grid(data, [nx,ny,nz], 1., bbox=bbox, nprocs=nprocs, periodicity=(False, False, False)) return ytCube(self, ds, spectral_factor=spectral_factor)
[docs] def to_glue(self, name=None, glue_app=None, dataset=None, start_gui=True): """ Send data to a new or existing Glue application Parameters ---------- name : str or None The name of the dataset within Glue. If None, defaults to 'SpectralCube'. If a dataset with the given name already exists, a new dataset with "_" appended will be added instead. glue_app : GlueApplication or None A glue application to send the data to. If this is not specified, a new glue application will be started if one does not already exist for this cube. Otherwise, the data will be sent to the existing glue application, `self._glue_app`. dataset : glue.core.Data or None An existing Data object to add the cube to. This is a good way to compare cubes with the same dimensions. Supercedes ``glue_app`` start_gui : bool Start the GUI when this is run. Set to `False` for testing. """ if name is None: name = 'SpectralCube' from glue.app.qt import GlueApplication from glue.core import DataCollection, Data from glue.core.coordinates import coordinates_from_header try: from glue.viewers.image.qt.data_viewer import ImageViewer except ImportError: from glue.viewers.image.qt.viewer_widget import ImageWidget as ImageViewer if dataset is not None: if name in [d.label for d in dataset.components]: name = name+"_" dataset[name] = self else: result = Data(label=name) result.coords = coordinates_from_header(self.header) result.add_component(self, name) if glue_app is None: if hasattr(self,'_glue_app'): glue_app = self._glue_app else: # Start a new glue session. This will quit when done. # I don't think the return statement is ever reached, based on # past attempts [@ChrisBeaumont - chime in here if you'd like] dc = DataCollection([result]) #start Glue ga = self._glue_app = GlueApplication(dc) self._glue_viewer = ga.new_data_viewer(ImageViewer, data=result) if start_gui: self._glue_app.start() return self._glue_app glue_app.add_datasets(self._glue_app.data_collection, result)
[docs] def to_pvextractor(self): """ Open the cube in a quick viewer written in matplotlib that allows you to create PV extractions within the GUI """ from pvextractor.gui import PVSlicer return PVSlicer(self)
[docs] def to_ds9(self, ds9id=None, newframe=False): """ Send the data to ds9 (this will create a copy in memory) Parameters ---------- ds9id: None or string The DS9 session ID. If 'None', a new one will be created. To find your ds9 session ID, open the ds9 menu option File:XPA:Information and look for the XPA_METHOD string, e.g. ``XPA_METHOD: 86ab2314:60063``. You would then calll this function as ``cube.to_ds9('86ab2314:60063')`` newframe: bool Send the cube to a new frame or to the current frame? """ try: import ds9 except ImportError: import pyds9 as ds9 if ds9id is None: dd = ds9.DS9(start=True) else: dd = ds9.DS9(target=ds9id, start=False) if newframe: dd.set('frame new') dd.set_pyfits(self.hdulist) return dd
@property def header(self): log.debug("Creating header") header = super(BaseSpectralCube, self).header # Preserve the cube's spectral units # (if CUNIT3 is not in the header, it is whatever that type's default unit is) if 'CUNIT3' in header and self._spectral_unit != u.Unit(header['CUNIT3']): header['CDELT3'] *= self._spectral_scale header['CRVAL3'] *= self._spectral_scale header['CUNIT3'] = self._spectral_unit.to_string(format='FITS') return header @property def hdu(self): """ HDU version of self """ log.debug("Creating HDU") hdu = PrimaryHDU(self.filled_data[:].value, header=self.header) return hdu @property def hdulist(self): return HDUList(self.hdu)
[docs] @warn_slow def to(self, unit, equivalencies=()): """ Return the cube converted to the given unit (assuming it is equivalent). If conversion was required, this will be a copy, otherwise it will """ if not isinstance(unit, u.Unit): unit = u.Unit(unit) if unit == self.unit: # No copying return self # Create the tuple of unit conversions needed. factor = cube_utils.bunit_converters(self, unit, equivalencies=equivalencies) # special case: array in equivalencies # (I don't think this should have to be special cased, but I don't know # how to manipulate broadcasting rules any other way) if hasattr(factor, '__len__') and len(factor) == len(self): return self._new_cube_with(data=self._data*factor[:,None,None], unit=unit) else: return self._new_cube_with(data=self._data*factor, unit=unit)
[docs] def find_lines(self, velocity_offset=None, velocity_convention=None, rest_value=None, **kwargs): """ Using astroquery's splatalogue interface, search for lines within the spectral band. See `astroquery.splatalogue.Splatalogue` for information on keyword arguments Parameters ---------- velocity_offset : u.km/u.s equivalent An offset by which the spectral axis should be shifted before searching splatalogue. This value will be *added* to the velocity, so if you want to redshift a spectrum, make this value positive, and if you want to un-redshift it, make this value negative. velocity_convention : 'radio', 'optical', 'relativistic' The doppler convention to pass to `with_spectral_unit` rest_value : u.GHz equivalent The rest frequency (or wavelength or energy) to be passed to `with_spectral_unit` """ warnings.warn("The line-finding routine is experimental. Please " "report bugs on the Issues page: " "https://github.com/radio-astro-tools/spectral-cube/issues", ExperimentalImplementationWarning ) from astroquery.splatalogue import Splatalogue if velocity_convention in DOPPLER_CONVENTIONS: velocity_convention = DOPPLER_CONVENTIONS[velocity_convention] if velocity_offset is not None: newspecaxis = self.with_spectral_unit(u.km/u.s, velocity_convention=velocity_convention, rest_value=rest_value).spectral_axis spectral_axis = (newspecaxis + velocity_offset).to(u.GHz, velocity_convention(rest_value)) else: spectral_axis = self.spectral_axis.to(u.GHz) numin,numax = spectral_axis.min(), spectral_axis.max() log.log(19, "Min/max frequency: {0},{1}".format(numin, numax)) result = Splatalogue.query_lines(numin, numax, **kwargs) return result
[docs] @warn_slow def reproject(self, header, order='bilinear', use_memmap=False, filled=True): """ Spatially reproject the cube into a new header. Fills the data with the cube's ``fill_value`` to replace bad values before reprojection. If you want to reproject a cube both spatially and spectrally, you need to use `spectral_interpolate` as well. .. warning:: The current implementation of ``reproject`` requires that the whole cube be loaded into memory. Issue #506 notes that this is a problem, and it is on our to-do list to fix. Parameters ---------- header : `astropy.io.fits.Header` A header specifying a cube in valid WCS order : int or str, optional The order of the interpolation (if ``mode`` is set to ``'interpolation'``). This can be either one of the following strings: * 'nearest-neighbor' * 'bilinear' * 'biquadratic' * 'bicubic' or an integer. A value of ``0`` indicates nearest neighbor interpolation. use_memmap : bool If specified, a memory mapped temporary file on disk will be written to rather than storing the intermediate spectra in memory. filled : bool Fill the masked values with the cube's fill value before reprojection? Note that setting ``filled=False`` will use the raw data array, which can be a workaround that prevents loading large data into memory. """ try: from reproject.version import version except ImportError: raise ImportError("Requires the reproject package to be" " installed.") # Need version > 0.2 to work with cubes, >= 0.5 for memmap from distutils.version import LooseVersion if LooseVersion(version) < "0.5": raise Warning("Requires version >=0.5 of reproject. The current " "version is: {}".format(version)) elif LooseVersion(version) >= "0.6": reproj_kwargs = {} else: reproj_kwargs = {'independent_celestial_slices': True} from reproject import reproject_interp # TODO: Find the minimal subcube that contains the header and only reproject that # (see FITS_tools.regrid_cube for a guide on how to do this) newwcs = wcs.WCS(header) shape_out = tuple([header['NAXIS{0}'.format(i + 1)] for i in range(header['NAXIS'])][::-1]) if filled: data = self.unitless_filled_data[:] else: data = self._data if use_memmap: if data.dtype.itemsize not in (4,8): raise ValueError("Data must be float32 or float64 to be " "reprojected. Other data types need some " "kind of additional memory handling.") # note: requires reproject from December 2018 or later outarray = np.memmap(filename='output.np', mode='w+', shape=tuple(shape_out), dtype='float64' if data.dtype.itemsize == 8 else 'float32') else: outarray = None newcube, newcube_valid = reproject_interp((data, self.header), newwcs, output_array=outarray, shape_out=shape_out, order=order, **reproj_kwargs) return self._new_cube_with(data=newcube, wcs=newwcs, mask=BooleanArrayMask(newcube_valid.astype('bool'), newwcs), meta=self.meta, )
[docs] @parallel_docstring def spatial_smooth_median(self, ksize, update_function=None, **kwargs): """ Smooth the image in each spatial-spatial plane of the cube using a median filter. Parameters ---------- ksize : int Size of the median filter (scipy.ndimage.filters.median_filter) update_function : method Method that is called to update an external progressbar If provided, it disables the default `astropy.utils.console.ProgressBar` kwargs : dict Passed to the convolve function """ if not scipyOK: raise ImportError("Scipy could not be imported: this function won't work.") def _msmooth_image(im, **kwargs): return ndimage.filters.median_filter(im, size=ksize, **kwargs) newcube = self.apply_function_parallel_spatial(_msmooth_image, **kwargs) return newcube
[docs] @parallel_docstring def spatial_smooth(self, kernel, convolve=convolution.convolve, **kwargs): """ Smooth the image in each spatial-spatial plane of the cube. Parameters ---------- kernel : `~astropy.convolution.Kernel2D` A 2D kernel from astropy convolve : function The astropy convolution function to use, either `astropy.convolution.convolve` or `astropy.convolution.convolve_fft` kwargs : dict Passed to the convolve function """ def _gsmooth_image(img, **kwargs): """ Helper function to smooth an image """ return convolve(img, kernel, normalize_kernel=True, **kwargs) newcube = self.apply_function_parallel_spatial(_gsmooth_image, **kwargs) return newcube
[docs] @parallel_docstring def spectral_smooth_median(self, ksize, use_memmap=True, verbose=0, num_cores=None, **kwargs): """ Smooth the cube along the spectral dimension Parameters ---------- ksize : int Size of the median filter (scipy.ndimage.filters.median_filter) verbose : int Verbosity level to pass to joblib kwargs : dict Not used at the moment. """ if not scipyOK: raise ImportError("Scipy could not be imported: this function won't work.") return self.apply_function_parallel_spectral(ndimage.filters.median_filter, size=ksize, verbose=verbose, num_cores=num_cores, use_memmap=use_memmap, **kwargs)
def _apply_function_parallel_base(self, iteration_data, function, applicator, num_cores=None, verbose=0, use_memmap=True, parallel=False, memmap_dir=None, update_function=None, **kwargs ): """ Apply a function in parallel using the ``applicator`` function. The function will be performed on data with masked values replaced with the cube's fill value. Parameters ---------- iteration_data : generator The data to be iterated over in the format expected by ``applicator`` function : function The function to apply in the spectral dimension. It must take two arguments: an array representing a spectrum and a boolean array representing the mask. It may also accept ``**kwargs``. The function must return an object with the same shape as the input spectrum. applicator : function Either ``_apply_spatial_function`` or ``_apply_spectral_function``, a tool to handle the iteration data and send it to the ``function`` appropriately. num_cores : int or None The number of cores to use if running in parallel. Should be >1 if ``parallel==True`` and cannot be >1 if ``parallel==False`` verbose : int Verbosity level to pass to joblib use_memmap : bool If specified, a memory mapped temporary file on disk will be written to rather than storing the intermediate spectra in memory. parallel : bool If set to ``False``, will force the use of a single thread instead of using ``joblib``. update_function : function A callback function to call on each iteration of the application. It should not accept any arguments. For example, this can be ``Progressbar.update`` or some function that prints a status report. The function *must* be picklable if ``parallel==True``. kwargs : dict Passed to ``function`` """ if use_memmap: ntf = tempfile.NamedTemporaryFile(dir=memmap_dir) outcube = np.memmap(ntf, mode='w+', shape=self.shape, dtype=np.float) else: if self._is_huge and not self.allow_huge_operations: raise ValueError("Applying a function without ``use_memmap`` " "requires loading the whole array into " "memory *twice*, which can overload the " "machine's memory for large cubes. Either " "set ``use_memmap=True`` or set " "``cube.allow_huge_operations=True`` to " "override this restriction.") outcube = np.empty(shape=self.shape, dtype=np.float) if num_cores == 1 and parallel: warnings.warn("parallel=True was specified but num_cores=1. " "Joblib will be used to run the task with a " "single thread.") elif num_cores is not None and num_cores > 1 and not parallel: raise ValueError("parallel execution was not requested, but " "multiple cores were: these are incompatible " "options. Either specify num_cores=1 or " "parallel=True") if parallel and use_memmap: # it is not possible to run joblib parallelization without memmap try: import joblib from joblib._parallel_backends import MultiprocessingBackend from joblib import register_parallel_backend, parallel_backend from joblib import Parallel, delayed if update_function is not None: # https://stackoverflow.com/questions/38483874/intermediate-results-from-joblib class MultiCallback: def __init__(self, *callbacks): self.callbacks = [cb for cb in callbacks if cb] def __call__(self, out): for cb in self.callbacks: cb(out) class Callback_Backend(MultiprocessingBackend): def callback(self, result): update_function() # Overload apply_async and set callback=self.callback def apply_async(self, func, callback=None): cbs = MultiCallback(callback, self.callback) return super().apply_async(func, cbs) joblib.register_parallel_backend('custom', Callback_Backend, make_default=True) Parallel(n_jobs=num_cores, verbose=verbose, max_nbytes=None)(delayed(applicator)(arg, outcube, function, **kwargs) for arg in iteration_data) except ImportError: if num_cores is not None and num_cores > 1: warnings.warn("Could not import joblib. Will run in serial.", warnings.ImportWarning) parallel = False # this isn't an else statement because we want to catch the case where # the above clause fails on ImportError if not parallel or not use_memmap: if update_function is not None: pbu = update_function elif verbose > 0: progressbar = ProgressBar(self.shape[1]*self.shape[2]) pbu = progressbar.update else: pbu = object for arg in iteration_data: applicator(arg, outcube, function, **kwargs) pbu() # TODO: do something about the mask? newcube = self._new_cube_with(data=outcube, wcs=self.wcs, mask=self.mask, meta=self.meta, fill_value=self.fill_value) return newcube
[docs] def apply_function_parallel_spatial(self, function, num_cores=None, verbose=0, use_memmap=True, parallel=True, **kwargs ): """ Apply a function in parallel along the spatial dimension. The function will be performed on data with masked values replaced with the cube's fill value. Parameters ---------- function : function The function to apply in the spatial dimension. It must take two arguments: an array representing an image and a boolean array representing the mask. It may also accept ``**kwargs``. The function must return an object with the same shape as the input spectrum. num_cores : int or None The number of cores to use if running in parallel verbose : int Verbosity level to pass to joblib use_memmap : bool If specified, a memory mapped temporary file on disk will be written to rather than storing the intermediate spectra in memory. parallel : bool If set to ``False``, will force the use of a single core without using ``joblib``. kwargs : dict Passed to ``function`` """ shape = self.shape data = self.unitless_filled_data # 'images' is a generator # the boolean check will skip the function for bad spectra images = ((data[ii,:,:], self.mask.include(view=(ii, slice(None), slice(None))), ii, ) for ii in range(shape[0])) return self._apply_function_parallel_base(images, function, applicator=_apply_spatial_function, verbose=verbose, parallel=parallel, num_cores=num_cores, use_memmap=use_memmap, **kwargs)
[docs] def apply_function_parallel_spectral(self, function, num_cores=None, verbose=0, use_memmap=True, parallel=True, **kwargs ): """ Apply a function in parallel along the spectral dimension. The function will be performed on data with masked values replaced with the cube's fill value. Parameters ---------- function : function The function to apply in the spectral dimension. It must take two arguments: an array representing a spectrum and a boolean array representing the mask. It may also accept ``**kwargs``. The function must return an object with the same shape as the input spectrum. num_cores : int or None The number of cores to use if running in parallel verbose : int Verbosity level to pass to joblib use_memmap : bool If specified, a memory mapped temporary file on disk will be written to rather than storing the intermediate spectra in memory. parallel : bool If set to ``False``, will force the use of a single core without using ``joblib``. kwargs : dict Passed to ``function`` """ shape = self.shape data = self.unitless_filled_data # 'spectra' is a generator # the boolean check will skip the function for bad spectra # TODO: should spatial good/bad be cached? spectra = ((data[:,jj,ii], self.mask.include(view=(slice(None), jj, ii)), ii, jj, ) for jj in range(shape[1]) for ii in range(shape[2])) return self._apply_function_parallel_base(iteration_data=spectra, function=function, applicator=_apply_spectral_function, use_memmap=use_memmap, parallel=parallel, verbose=verbose, num_cores=num_cores, **kwargs )
[docs] @parallel_docstring def sigma_clip_spectrally(self, threshold, verbose=0, use_memmap=True, num_cores=None, **kwargs): """ Run astropy's sigma clipper along the spectral axis, converting all bad (excluded) values to NaN. Parameters ---------- threshold : float The ``sigma`` parameter in `astropy.stats.sigma_clip`, which refers to the number of sigma above which to cut. verbose : int Verbosity level to pass to joblib """ return self.apply_function_parallel_spectral(stats.sigma_clip, sigma=threshold, axis=0, # changes behavior of sigmaclip num_cores=num_cores, use_memmap=use_memmap, verbose=verbose, **kwargs)
[docs] @parallel_docstring def spectral_smooth(self, kernel, convolve=convolution.convolve, verbose=0, use_memmap=True, num_cores=None, **kwargs): """ Smooth the cube along the spectral dimension Note that the mask is left unchanged in this operation. Parameters ---------- kernel : `~astropy.convolution.Kernel1D` A 1D kernel from astropy convolve : function The astropy convolution function to use, either `astropy.convolution.convolve` or `astropy.convolution.convolve_fft` verbose : int Verbosity level to pass to joblib kwargs : dict Passed to the convolve function """ if isinstance(kernel.array, u.Quantity): raise u.UnitsError("The convolution kernel should be defined " "without a unit.") return self.apply_function_parallel_spectral(convolve, kernel=kernel, normalize_kernel=True, num_cores=num_cores, use_memmap=use_memmap, verbose=verbose, **kwargs)
[docs] def spectral_interpolate(self, spectral_grid, suppress_smooth_warning=False, fill_value=None, update_function=None): """Resample the cube spectrally onto a specific grid Parameters ---------- spectral_grid : array An array of the spectral positions to regrid onto suppress_smooth_warning : bool If disabled, a warning will be raised when interpolating onto a grid that does not nyquist sample the existing grid. Disable this if you have already appropriately smoothed the data. fill_value : float Value for extrapolated spectral values that lie outside of the spectral range defined in the original data. The default is to use the nearest spectral channel in the cube. update_function : method Method that is called to update an external progressbar If provided, it disables the default `astropy.utils.console.ProgressBar` Returns ------- cube : SpectralCube """ inaxis = self.spectral_axis.to(spectral_grid.unit) indiff = np.mean(np.diff(inaxis)) outdiff = np.mean(np.diff(spectral_grid)) # account for reversed axes if outdiff < 0: spectral_grid = spectral_grid[::-1] outdiff = np.mean(np.diff(spectral_grid)) outslice = slice(None, None, -1) else: outslice = slice(None, None, 1) cubedata = self.filled_data specslice = slice(None) if indiff >= 0 else slice(None, None, -1) inaxis = inaxis[specslice] indiff = np.mean(np.diff(inaxis)) # insanity checks if indiff < 0 or outdiff < 0: raise ValueError("impossible.") assert np.all(np.diff(spectral_grid) > 0) assert np.all(np.diff(inaxis) > 0) np.testing.assert_allclose(np.diff(spectral_grid), outdiff, err_msg="Output grid must be linear") if outdiff > 2 * indiff and not suppress_smooth_warning: warnings.warn("Input grid has too small a spacing. The data should " "be smoothed prior to resampling.", SmoothingWarning ) newcube = np.empty([spectral_grid.size, self.shape[1], self.shape[2]], dtype=cubedata[:1, 0, 0].dtype) newmask = np.empty([spectral_grid.size, self.shape[1], self.shape[2]], dtype='bool') yy,xx = np.indices(self.shape[1:]) if update_function is None: pb = ProgressBar(xx.size) update_function = pb.update for ix, iy in (zip(xx.flat, yy.flat)): mask = self.mask.include(view=(specslice, iy, ix)) if any(mask): newcube[outslice,iy,ix] = \ np.interp(spectral_grid.value, inaxis.value, cubedata[specslice,iy,ix].value, left=fill_value, right=fill_value) if all(mask): newmask[:,iy,ix] = True else: interped = np.interp(spectral_grid.value, inaxis.value, mask) > 0 newmask[outslice,iy,ix] = interped else: newmask[:, iy, ix] = False newcube[:, iy, ix] = np.NaN update_function() newwcs = self.wcs.deepcopy() newwcs.wcs.crpix[2] = 1 newwcs.wcs.crval[2] = spectral_grid[0].value if outslice.step > 0 \ else spectral_grid[-1].value newwcs.wcs.cunit[2] = spectral_grid.unit.to_string('FITS') newwcs.wcs.cdelt[2] = outdiff.value if outslice.step > 0 \ else -outdiff.value newwcs.wcs.set() newbmask = BooleanArrayMask(newmask, wcs=newwcs) newcube = self._new_cube_with(data=newcube, wcs=newwcs, mask=newbmask, meta=self.meta, fill_value=self.fill_value) return newcube
[docs] @warn_slow def convolve_to(self, beam, convolve=convolution.convolve_fft, update_function=None, **kwargs): """ Convolve each channel in the cube to a specified beam .. warning:: The current implementation of ``convolve_to`` creates an in-memory copy of the whole cube to store the convolved data. Issue #506 notes that this is a problem, and it is on our to-do list to fix. Parameters ---------- beam : `radio_beam.Beam` The beam to convolve to convolve : function The astropy convolution function to use, either `astropy.convolution.convolve` or `astropy.convolution.convolve_fft` update_function : method Method that is called to update an external progressbar If provided, it disables the default `astropy.utils.console.ProgressBar` kwargs : dict Keyword arguments to pass to the convolution function Returns ------- cube : `SpectralCube` A SpectralCube with a single ``beam`` """ # Check if the beams are the same. if beam == self.beam: warnings.warn("The given beam is identical to the current beam. " "Skipping convolution.") return self pixscale = wcs.utils.proj_plane_pixel_area(self.wcs.celestial)**0.5*u.deg convolution_kernel = beam.deconvolve(self.beam).as_kernel(pixscale) # See #631: kwargs get passed within self.apply_function_parallel_spatial def convfunc(img, **kwargs): return convolve(img, convolution_kernel, normalize_kernel=True, **kwargs) newcube = self.apply_function_parallel_spatial(convfunc, **kwargs).with_beam(beam) return newcube
[docs] def mask_channels(self, goodchannels): """ Helper function to mask out channels. This function is equivalent to adding a mask with ``cube[view]`` where ``view`` is broadcastable to the cube shape, but it accepts 1D arrays that are not normally broadcastable. Parameters ---------- goodchannels : array A 1D boolean array declaring which channels should be kept. Returns ------- cube : `SpectralCube` A cube with the specified channels masked """ goodchannels = np.asarray(goodchannels, dtype='bool') if goodchannels.ndim != 1: raise ValueError("goodchannels mask must be one-dimensional") if goodchannels.size != self.shape[0]: raise ValueError("goodchannels must have a length equal to the " "cube's spectral dimension.") return self.with_mask(goodchannels[:,None,None])
[docs] @warn_slow def downsample_axis(self, factor, axis, estimator=np.nanmean, truncate=False, use_memmap=True, progressbar=True): """ Downsample the cube by averaging over *factor* pixels along an axis. Crops right side if the shape is not a multiple of factor. The WCS will be 'downsampled' by the specified factor as well. If the downsample factor is odd, there will be an offset in the WCS. There is both an in-memory and a memory-mapped implementation; the default is to use the memory-mapped version. Technically, the 'large data' warning doesn't apply when using the memory-mapped version, but the warning is still there anyway. Parameters ---------- myarr : `~numpy.ndarray` The array to downsample factor : int The factor to downsample by axis : int The axis to downsample along estimator : function defaults to mean. You can downsample by summing or something else if you want a different estimator (e.g., downsampling error: you want to sum & divide by sqrt(n)) truncate : bool Whether to truncate the last chunk or average over a smaller number. e.g., if you downsample [1,2,3,4] by a factor of 3, you could get either [2] or [2,4] if truncate is True or False, respectively. use_memmap : bool Use a memory map on disk to avoid loading the whole cube into memory (several times)? If set, the warning about large cubes can be ignored (though you still have to override the warning) progressbar : bool Include a progress bar? Only works with ``use_memmap=True`` """ def makeslice(startpoint,axis=axis,step=factor): # make empty slices view = [slice(None) for ii in range(self.ndim)] # then fill the appropriate slice view[axis] = slice(startpoint,None,step) return tuple(view) # size of the dimension of interest xs = self.shape[axis] if not use_memmap: if xs % int(factor) != 0: if truncate: view = [slice(None) for ii in range(self.ndim)] view[axis] = slice(None,xs-(xs % int(factor))) view = tuple(view) crarr = self.unitless_filled_data[view] mask = self.mask[view].include() else: extension_shape = list(self.shape) extension_shape[axis] = (factor - xs % int(factor)) extension = np.empty(extension_shape) * np.nan crarr = np.concatenate((self.unitless_filled_data[:], extension), axis=axis) extension[:] = 0 mask = np.concatenate((self.mask.include(), extension), axis=axis) else: crarr = self.unitless_filled_data[:] mask = self.mask.include() # The extra braces here are crucial: We're adding an extra dimension so we # can average across it stacked_array = np.concatenate([[crarr[makeslice(ii)]] for ii in range(factor)]) dsarr = estimator(stacked_array, axis=0) if not isinstance(mask, np.ndarray): raise TypeError("Mask is of wrong data type") stacked_mask = np.concatenate([[mask[makeslice(ii)]] for ii in range(factor)]) mask = np.any(stacked_mask, axis=0) else: def makeslice_local(startpoint, axis=axis, nsteps=factor): # make empty slices view = [slice(None) for ii in range(self.ndim)] # then fill the appropriate slice view[axis] = slice(startpoint,startpoint+nsteps,1) return tuple(view) newshape = list(self.shape) newshape[axis] = (newshape[axis]//factor + ((1-int(truncate)) * (xs % int(factor) != 0))) newshape = tuple(newshape) if progressbar: progressbar = ProgressBar else: progressbar = lambda x: x # Create a view that will add a blank newaxis at the right spot view_newaxis = [slice(None) for ii in range(self.ndim)] view_newaxis[axis] = None view_newaxis = tuple(view_newaxis) ntf = tempfile.NamedTemporaryFile() dsarr = np.memmap(ntf, mode='w+', shape=newshape, dtype=np.float) ntf2 = tempfile.NamedTemporaryFile() mask = np.memmap(ntf2, mode='w+', shape=newshape, dtype=np.bool) for ii in progressbar(range(newshape[axis])): view_fulldata = makeslice_local(ii*factor) view_newdata = makeslice_local(ii, nsteps=1) to_average = self.unitless_filled_data[view_fulldata] to_anyfy = self.mask[view_fulldata].include() dsarr[view_newdata] = estimator(to_average, axis)[view_newaxis] mask[view_newdata] = np.any(to_anyfy, axis).astype('bool')[view_newaxis] # the slice should just start at zero; we had factor//2 here earlier, # and that was an error that probably half-compensated for an error in # wcs_utils view = makeslice(0) newwcs = wcs_utils.slice_wcs(self.wcs, view, shape=self.shape) newwcs._naxis = list(self.shape) # this is an assertion to ensure that the WCS produced is valid # (this is basically a regression test for #442) assert newwcs[:, slice(None), slice(None)] assert len(newwcs._naxis) == 3 return self._new_cube_with(data=dsarr, wcs=newwcs, mask=BooleanArrayMask(mask, wcs=newwcs))
[docs] def plot_channel_maps(self, nx, ny, channels, contourkwargs={}, output_file=None, fig=None, fig_smallest_dim_inches=8, decimals=3, zoom=1, textcolor=None, cmap='gray_r', tighten=False, textxloc=0.5, textyloc=0.9, savefig_kwargs={}, **kwargs): """ Make channel maps from a spectral cube Parameters ---------- input_file : str Name of the input spectral cube nx, ny : int Number of sub-plots in the x and y direction channels : list List of channels to show cmap : str The name of a colormap to use for the ``imshow`` colors contourkwargs : dict Keyword arguments passed to ``contour`` textcolor : None or str Color of the label text to overlay. If ``None``, will be determined automatically. If ``'notext'``, no text will be added. textxloc : float textyloc : float Text label X,Y-location in axis fraction units output_file : str Name of the matplotlib plot fig : matplotlib figure The figure object to plot onto. Will be overridden to enforce a specific aspect ratio. fig_smallest_dim_inches : float The size of the smallest dimension (either width or height) of the figure in inches. The other dimension will be selected based on the aspect ratio of the data: it cannot be a free parameter. decimals : int, optional Number of decimal places to show in spectral value zoom : int, optional How much to zoom in. In future versions of this function, the pointing center will be customizable. tighten : bool Call ``plt.tight_layout()`` after plotting? savefig_kwargs : dict Keyword arguments to pass to ``savefig`` (e.g., ``bbox_inches='tight'``) kwargs : dict Passed to ``imshow`` """ import matplotlib.pyplot as plt from matplotlib.gridspec import GridSpec cmap = getattr(plt.cm, cmap) if len(channels) != nx * ny: raise ValueError("Number of channels should be equal to nx * ny") # Read in spectral cube and get spectral axis spectral_axis = self.spectral_axis sizey, sizex = self.shape[1:] cenx = sizex / 2. ceny = sizey / 2. aspect_ratio = self.shape[2]/float(self.shape[1]) gridratio = ny / float(nx) * aspect_ratio if gridratio > 1: ysize = fig_smallest_dim_inches*gridratio xsize = fig_smallest_dim_inches else: xsize = fig_smallest_dim_inches*gridratio ysize = fig_smallest_dim_inches if fig is None: fig = plt.figure(figsize=(xsize, ysize)) else: fig.set_figheight(ysize) fig.set_figwidth(xsize) # unclear if needed #fig.subplots_adjust(margin,margin,1.-margin,1.-margin,0.,0.) axis_list = [] gs = GridSpec(ny, nx, figure=fig, hspace=0, wspace=0) for ichannel, channel in enumerate(channels): slc = self[channel,:,:] ax = plt.subplot(gs[ichannel], projection=slc.wcs) im = ax.imshow(slc.value, origin='lower', cmap=cmap, **kwargs) if contourkwargs: ax.contour(slc.value, **contourkwargs) ax.set_xlim(cenx - cenx / zoom, cenx + cenx / zoom) ax.set_ylim(ceny - ceny / zoom, ceny + ceny / zoom) if textcolor != 'notext': if textcolor is None: # determine average image color and set textcolor to opposite # (this is a bit hacky and there is _definitely_ a better way # to do this) avgcolor = im.cmap(im.norm(im.get_array())).mean(axis=(0,1)) totalcolor = avgcolor[:3].sum() if totalcolor > 0.5: textcolor = 'w' else: textcolor = 'k' ax.tick_params(color=textcolor) ax.set_title(("{0:." + str(decimals) + "f}").format(spectral_axis[channel]), x=textxloc, y=textyloc, color=textcolor) # only label bottom-left panel with locations if (ichannel != nx*(ny-1)): ax.coords[0].set_ticklabel_position('') ax.coords[1].set_ticklabel_position('') ax.tick_params(direction='in') axis_list.append(ax) if tighten: plt.tight_layout() if output_file is not None: fig.savefig(output_file, **savefig_kwargs) return axis_list
[docs]class SpectralCube(BaseSpectralCube, BeamMixinClass): __name__ = "SpectralCube" _oned_spectrum = OneDSpectrum def __new__(cls, *args, **kwargs): if kwargs.pop('use_dask', False): from .dask_spectral_cube import DaskSpectralCube return super().__new__(DaskSpectralCube) else: return super().__new__(cls) def __init__(self, data, wcs, mask=None, meta=None, fill_value=np.nan, header=None, allow_huge_operations=False, beam=None, wcs_tolerance=0.0, use_dask=False, **kwargs): super(SpectralCube, self).__init__(data=data, wcs=wcs, mask=mask, meta=meta, fill_value=fill_value, header=header, allow_huge_operations=allow_huge_operations, wcs_tolerance=wcs_tolerance, **kwargs) # Beam loading must happen *after* WCS is read if beam is None: beam = cube_utils.try_load_beam(self.header) else: if not isinstance(beam, Beam): raise TypeError("beam must be a radio_beam.Beam object.") # Allow setting the beam attribute even if there is no beam defined # Accessing `SpectralCube.beam` without a beam defined raises a # `NoBeamError` with an informative message. self.beam = beam if beam is not None: self._meta['beam'] = beam self._header.update(beam.to_header_keywords()) def _new_cube_with(self, **kwargs): beam = kwargs.pop('beam', None) if 'beam' in self._meta and beam is None: beam = self._beam newcube = super(SpectralCube, self)._new_cube_with(beam=beam, **kwargs) return newcube _new_cube_with.__doc__ = BaseSpectralCube._new_cube_with.__doc__
[docs] def with_beam(self, beam): ''' Attach a beam object to the `~SpectralCube`. Parameters ---------- beam : `~radio_beam.Beam` `Beam` object defining the resolution element of the `~SpectralCube`. ''' if not isinstance(beam, Beam): raise TypeError("beam must be a radio_beam.Beam object.") meta = self._meta.copy() meta['beam'] = beam header = self._header.copy() header.update(beam.to_header_keywords()) newcube = self._new_cube_with(meta=self.meta, beam=beam) return newcube
[docs]class VaryingResolutionSpectralCube(BaseSpectralCube, MultiBeamMixinClass): """ A variant of the SpectralCube class that has PSF (beam) information on a per-channel basis. """ __name__ = "VaryingResolutionSpectralCube" _oned_spectrum = VaryingResolutionOneDSpectrum def __new__(cls, *args, **kwargs): if kwargs.pop('use_dask', False): from .dask_spectral_cube import DaskVaryingResolutionSpectralCube return super().__new__(DaskVaryingResolutionSpectralCube) else: return super().__new__(cls) def __init__(self, *args, **kwargs): """ Create a SpectralCube with an associated beam table. The new VaryingResolutionSpectralCube will have a ``beams`` attribute and a ``beam_threshold`` attribute as described below. It will perform some additional checks when trying to perform analysis across image frames. Three new keyword arguments are accepted: Other Parameters ---------------- beam_table : `numpy.recarray` A table of beam major and minor axes in arcseconds and position angles, with labels BMAJ, BMIN, BPA beams : list A list of `radio_beam.Beam` objects beam_threshold : float or dict The fractional threshold above which beams are considered different. A dictionary may be used with entries 'area', 'major', 'minor', 'pa' so that you can specify a different fractional threshold for each of these. For example, if you want to check only that the areas are the same, and not worry about the shape (which might be a bad idea...), you could set ``beam_threshold={'area':0.01, 'major':1.5, 'minor':1.5, 'pa':5.0}`` """ # these types of cube are undefined without the radio_beam package beam_table = kwargs.pop('beam_table', None) beams = kwargs.pop('beams', None) beam_threshold = kwargs.pop('beam_threshold', 0.01) if (beam_table is None and beams is None): raise ValueError( "Must give either a beam table or a list of beams to " "initialize a VaryingResolutionSpectralCube") super(VaryingResolutionSpectralCube, self).__init__(*args, **kwargs) if isinstance(beam_table, BinTableHDU): beam_data_table = beam_table.data else: beam_data_table = beam_table if beam_table is not None: # CASA beam tables are in arcsec, and that's what we support beams = Beams(major=u.Quantity(beam_data_table['BMAJ'], u.arcsec), minor=u.Quantity(beam_data_table['BMIN'], u.arcsec), pa=u.Quantity(beam_data_table['BPA'], u.deg), meta=[{key: row[key] for key in beam_data_table.names if key not in ('BMAJ','BPA', 'BMIN')} for row in beam_data_table], ) goodbeams = beams.isfinite # track which, if any, beams are masked for later use self.goodbeams_mask = goodbeams if not all(goodbeams): warnings.warn("There were {0} non-finite beams; layers with " "non-finite beams will be masked out.".format( np.count_nonzero(np.logical_not(goodbeams))), NonFiniteBeamsWarning ) beam_mask = BooleanArrayMask(goodbeams[:,None,None], wcs=self._wcs, shape=self.shape, ) if not is_broadcastable_and_smaller(beam_mask.shape, self._data.shape): # this should never be allowed to happen raise ValueError("Beam mask shape is not broadcastable to data shape: " "%s vs %s" % (beam_mask.shape, self._data.shape)) assert beam_mask.shape == self.shape new_mask = np.bitwise_and(self._mask, beam_mask) new_mask._validate_wcs(new_data=self._data, new_wcs=self._wcs) self._mask = new_mask if (len(beams) != self.shape[0]): raise ValueError("Beam list must have same size as spectral " "dimension") self.beams = beams self.beam_threshold = beam_threshold def __getitem__(self, view): # Need to allow self[:], self[:,:] if isinstance(view, (slice,int,np.int64)): view = (view, slice(None), slice(None)) elif len(view) == 2: view = view + (slice(None),) elif len(view) > 3: raise IndexError("Too many indices") meta = {} meta.update(self._meta) slice_data = [(s.start, s.stop, s.step) if hasattr(s,'start') else s for s in view] if 'slice' in meta: meta['slice'].append(slice_data) else: meta['slice'] = [slice_data] # intslices identifies the slices that are given by integers, i.e. # indices. Other slices are slice objects, e.g. obj[5:10], and have # 'start' attributes. intslices = [2-ii for ii,s in enumerate(view) if not hasattr(s,'start')] # for beams, we care only about the first slice, independent of its # type specslice = view[0] if intslices: if len(intslices) > 1: if 2 in intslices: raise NotImplementedError("1D slices along non-spectral " "axes are not yet implemented.") newwcs = self._wcs.sub([a for a in (1,2,3) if a not in [x+1 for x in intslices]]) if cube_utils._has_beam(self): bmarg = {'beam': self.beam} elif cube_utils._has_beams(self): bmarg = {'beams': self.unmasked_beams[specslice]} else: bmarg = {} return self._oned_spectrum(value=self._data[view], wcs=newwcs, copy=False, unit=self.unit, spectral_unit=self._spectral_unit, mask=self.mask[view], meta=meta, goodbeams_mask=self.goodbeams_mask[specslice] if hasattr(self, '_goodbeams_mask') else None, **bmarg ) # only one element, so drop an axis newwcs = wcs_utils.drop_axis(self._wcs, intslices[0]) header = self._nowcs_header # Slice objects know how to parse Beam objects stored in the # metadata # A 2D slice with a VRSC should not be allowed along a # position-spectral axis if not isinstance(self.unmasked_beams[specslice], Beam): raise AttributeError("2D slices along a spectral axis are not " "allowed for " "VaryingResolutionSpectralCubes. Convolve" " to a common resolution with " "`convolve_to` before attempting " "position-spectral slicing.") meta['beam'] = self.unmasked_beams[specslice] return Slice(value=self.filled_data[view], wcs=newwcs, copy=False, unit=self.unit, header=header, meta=meta) newmask = self._mask[view] if self._mask is not None else None newwcs = wcs_utils.slice_wcs(self._wcs, view, shape=self.shape) newwcs._naxis = list(self.shape) # this is an assertion to ensure that the WCS produced is valid # (this is basically a regression test for #442) assert newwcs[:, slice(None), slice(None)] assert len(newwcs._naxis) == 3 return self._new_cube_with(data=self._data[view], wcs=newwcs, mask=newmask, beams=self.unmasked_beams[specslice], meta=meta)
[docs] def spectral_slab(self, lo, hi): """ Extract a new cube between two spectral coordinates Parameters ---------- lo, hi : :class:`~astropy.units.Quantity` The lower and upper spectral coordinate for the slab range. The units should be compatible with the units of the spectral axis. If the spectral axis is in frequency-equivalent units and you want to select a range in velocity, or vice-versa, you should first use :meth:`~spectral_cube.SpectralCube.with_spectral_unit` to convert the units of the spectral axis. """ # Find range of values for spectral axis ilo = self.closest_spectral_channel(lo) ihi = self.closest_spectral_channel(hi) if ilo > ihi: ilo, ihi = ihi, ilo ihi += 1 # Create WCS slab wcs_slab = self._wcs.deepcopy() wcs_slab.wcs.crpix[2] -= ilo # Create mask slab if self._mask is None: mask_slab = None else: try: mask_slab = self._mask[ilo:ihi, :, :] except NotImplementedError: warnings.warn("Mask slicing not implemented for " "{0} - dropping mask". format(self._mask.__class__.__name__), NotImplementedWarning ) mask_slab = None # Create new spectral cube slab = self._new_cube_with(data=self._data[ilo:ihi], wcs=wcs_slab, beams=self.unmasked_beams[ilo:ihi], mask=mask_slab) return slab
def _new_cube_with(self, goodbeams_mask=None, **kwargs): beams = kwargs.pop('beams', self.unmasked_beams) beam_threshold = kwargs.pop('beam_threshold', self.beam_threshold) VRSC = VaryingResolutionSpectralCube newcube = super(VRSC, self)._new_cube_with(beams=beams, beam_threshold=beam_threshold, **kwargs) if goodbeams_mask is not None: newcube.goodbeams_mask = goodbeams_mask assert hasattr(newcube, '_goodbeams_mask') else: newcube.goodbeams_mask = np.isfinite(newcube.beams) assert hasattr(newcube, '_goodbeams_mask') return newcube _new_cube_with.__doc__ = BaseSpectralCube._new_cube_with.__doc__ def _check_beam_areas(self, threshold, mean_beam, mask=None): """ Check that the beam areas are the same to within some threshold """ if mask is not None: assert len(mask) == len(self.unmasked_beams) mask = np.array(mask, dtype='bool') else: mask = np.ones(len(self.unmasked_beams), dtype='bool') qtys = dict(sr=self.unmasked_beams.sr, major=self.unmasked_beams.major.to(u.deg), minor=self.unmasked_beams.minor.to(u.deg), # position angles are not really comparable #pa=u.Quantity([bm.pa for bm in self.unmasked_beams], u.deg), ) errormessage = "" for (qtyname, qty) in (qtys.items()): minv = qty[mask].min() maxv = qty[mask].max() mn = getattr(mean_beam, qtyname) maxdiff = (np.max(np.abs(u.Quantity((maxv-mn, minv-mn))))/mn).decompose() if isinstance(threshold, dict): th = threshold[qtyname] else: th = threshold if maxdiff > th: errormessage += ("Beam {2}s differ by up to {0}x, which is greater" " than the threshold {1}\n".format(maxdiff, threshold, qtyname )) if errormessage != "": raise ValueError(errormessage) def __getattribute__(self, attrname): """ For any functions that operate over the spectral axis, perform beam sameness checks before performing the operation to avoid unexpected results """ # short name to avoid long lines below VRSC = VaryingResolutionSpectralCube # what about apply_numpy_function, apply_function? since they're # called by some of these, maybe *only* those should be wrapped to # avoid redundant calls if attrname in ('moment', 'apply_numpy_function', 'apply_function', 'apply_function_parallel_spectral'): origfunc = super(VRSC, self).__getattribute__(attrname) return self._handle_beam_areas_wrapper(origfunc) else: return super(VRSC, self).__getattribute__(attrname) @property def header(self): header = super(VaryingResolutionSpectralCube, self).header # this indicates to CASA that there is a beam table header['CASAMBM'] = True return header @property def hdu(self): raise ValueError("For VaryingResolutionSpectralCube's, use hdulist " "instead of hdu.") @property def hdulist(self): """ HDUList version of self """ hdu = PrimaryHDU(self.filled_data[:].value, header=self.header) from .cube_utils import beams_to_bintable # use unmasked beams because, even if the beam is masked out, we should # write it bmhdu = beams_to_bintable(self.unmasked_beams) return HDUList([hdu, bmhdu])
[docs] @warn_slow def convolve_to(self, beam, allow_smaller=False, convolve=convolution.convolve_fft, update_function=None, **kwargs): """ Convolve each channel in the cube to a specified beam .. warning:: The current implementation of ``convolve_to`` creates an in-memory copy of the whole cube to store the convolved data. Issue #506 notes that this is a problem, and it is on our to-do list to fix. .. warning:: Note that if there is any misaligment between the cube's spatial pixel axes and the WCS's spatial axes *and* the beams are not round, the convolution kernels used here may be incorrect. Be wary in such cases! Parameters ---------- beam : `radio_beam.Beam` The beam to convolve to allow_smaller : bool If the specified target beam is smaller than the beam in a channel in any dimension and this is ``False``, it will raise an exception. convolve : function The astropy convolution function to use, either `astropy.convolution.convolve` or `astropy.convolution.convolve_fft` update_function : method Method that is called to update an external progressbar If provided, it disables the default `astropy.utils.console.ProgressBar` kwargs : dict Keyword arguments to pass to the convolution function Returns ------- cube : `SpectralCube` A SpectralCube with a single ``beam`` """ if ((self.wcs.celestial.wcs.get_pc()[0,1] != 0 or self.wcs.celestial.wcs.get_pc()[1,0] != 0)): warnings.warn("The beams will produce convolution kernels " "that are not aware of any misaligment " "between pixel and world coordinates, " "and there are off-diagonal elements of the " "WCS spatial transformation matrix. " "Unexpected results are likely.", BeamWarning ) pixscale = wcs.utils.proj_plane_pixel_area(self.wcs.celestial)**0.5*u.deg convolution_kernels = [] for bm,valid in zip(self.unmasked_beams, self.goodbeams_mask): if not valid: # just skip masked-out beams convolution_kernels.append(None) continue elif beam == bm: # Point response when beams are equal, don't convolve. convolution_kernels.append(None) continue try: cb = beam.deconvolve(bm) ck = cb.as_kernel(pixscale) convolution_kernels.append(ck) except ValueError: if allow_smaller: convolution_kernels.append(None) else: raise if update_function is None: pb = ProgressBar(self.shape[0]) update_function = pb.update newdata = np.empty(self.shape) for ii,kernel in enumerate(convolution_kernels): # load each image from a slice to avoid loading whole cube into # memory img = self[ii,:,:].filled_data[:] # Kernel can only be None when `allow_smaller` is True, # or if the beams are equal. Only the latter is really valid. if kernel is None: newdata[ii, :, :] = img else: # See #631: kwargs get passed within self.apply_function_parallel_spatial newdata[ii, :, :] = convolve(img, kernel, normalize_kernel=True, **kwargs) update_function() newcube = SpectralCube(data=newdata, wcs=self.wcs, mask=self.mask, meta=self.meta, fill_value=self.fill_value, header=self.header, allow_huge_operations=self.allow_huge_operations, beam=beam, wcs_tolerance=self._wcs_tolerance) return newcube
[docs] @warn_slow def to(self, unit, equivalencies=()): """ Return the cube converted to the given unit (assuming it is equivalent). If conversion was required, this will be a copy, otherwise it will """ if not isinstance(unit, u.Unit): unit = u.Unit(unit) if unit == self.unit: # No copying return self # Create the tuple of unit conversions needed. factor = cube_utils.bunit_converters(self, unit, equivalencies=equivalencies) factor = np.array(factor) # special case: array in equivalencies # (I don't think this should have to be special cased, but I don't know # how to manipulate broadcasting rules any other way) if hasattr(factor, '__len__') and len(factor) == len(self): return self._new_cube_with(data=self._data*factor[:,None,None], unit=unit) else: return self._new_cube_with(data=self._data*factor, unit=unit)
[docs] def mask_channels(self, goodchannels): """ Helper function to mask out channels. This function is equivalent to adding a mask with ``cube[view]`` where ``view`` is broadcastable to the cube shape, but it accepts 1D arrays that are not normally broadcastable. Additionally, for `VaryingResolutionSpectralCube` s, the beams in the bad channels will not be checked when averaging, convolving, and doing other operations that are multibeam-aware. Parameters ---------- goodchannels : array A 1D boolean array declaring which channels should be kept. Returns ------- cube : `SpectralCube` A cube with the specified channels masked """ goodchannels = np.asarray(goodchannels, dtype='bool') if goodchannels.ndim != 1: raise ValueError("goodchannels mask must be one-dimensional") if goodchannels.size != self.shape[0]: raise ValueError("goodchannels must have a length equal to the " "cube's spectral dimension.") cube = self.with_mask(goodchannels[:,None,None]) cube.goodbeams_mask = np.logical_and(goodchannels, self.goodbeams_mask) return cube
[docs] def spectral_interpolate(self, *args, **kwargs): raise AttributeError("VaryingResolutionSpectralCubes can't be " "spectrally interpolated. Convolve to a " "common resolution with `convolve_to` before " "attempting spectral interpolation.")
[docs] def spectral_smooth(self, *args, **kwargs): raise AttributeError("VaryingResolutionSpectralCubes can't be " "spectrally smoothed. Convolve to a " "common resolution with `convolve_to` before " "attempting spectral smoothed.")
def _regionlist_to_single_region(region_list): """ Recursively merge a region list into a single compound region """ import regions if len(region_list) == 1: return region_list[0] left = _regionlist_to_single_region(region_list[:len(region_list)//2]) right = _regionlist_to_single_region(region_list[len(region_list)//2:]) return regions.CompoundPixelRegion(left, right, operator.or_)