Source code for gwcs.coordinate_frames

# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
Defines coordinate frames and ties them to data axes.
"""
import logging
import numpy as np

from astropy.utils.misc import isiterable
from astropy import time
from astropy import units as u
from astropy import utils as astutil
from astropy import coordinates as coord
from astropy.wcs.wcsapi.low_level_api import (validate_physical_types,
                                              VALID_UCDS)


__all__ = ['Frame2D', 'CelestialFrame', 'SpectralFrame', 'CompositeFrame',
           'CoordinateFrame', 'TemporalFrame']


UCD1_TO_CTYPE = {
    'pos.eq.ra': 'RA',
    'pos.eq.dec': 'DEC',
    'pos.galactic.lon': 'GLON',
    'pos.galactic.lat': 'GLAT',
    'pos.ecliptic.lon': 'ELON',
    'pos.ecliptic.lat': 'ELAT',
    'pos.bodyrc.lon': 'TLON',
    'pos.bodyrc.lat': 'TLAT',
    'custom:pos.helioprojective.lat': 'HPLT',
    'custom:pos.helioprojective.lon': 'HPLN',
    'custom:pos.heliographic.stonyhurst.lon': 'HGLN',
    'custom:pos.heliographic.stonyhurst.lat': 'HGLT',
    'custom:pos.heliographic.carrington.lon': 'CRLN',
    'custom:pos.heliographic.carrington.lat': 'CRLT',
    'em.freq': 'FREQ',
    'em.energy': 'ENER',
    'em.wavenumber': 'WAVN',
    'em.wl': 'WAVE',
    'spect.dopplerVeloc.radio': 'VRAD',
    'spect.dopplerVeloc.opt': 'VOPT',
    'src.redshift': 'ZOPT',
    'spect.dopplerVeloc': 'VELO',
    'custom:spect.doplerVeloc.beta': 'BETA',
    'time': 'TIME',
    }


STANDARD_REFERENCE_FRAMES = [frame.upper() for frame in coord.builtin_frames.__all__]

STANDARD_REFERENCE_POSITION = ["GEOCENTER", "BARYCENTER", "HELIOCENTER",
                               "TOPOCENTER", "LSR", "LSRK", "LSRD",
                               "GALACTIC_CENTER", "LOCAL_GROUP_CENTER"]


def get_ctype_from_ucd(ucd):
    """
    Return the FITS ``CTYPE`` corresponding to a UCD1 value.

    Parameters
    ----------
    ucd : str
        UCD string, for example one of ```WCS.world_axis_physical_types``.

    Returns
    -------
    CTYPE : str
        The corresponding FITS ``CTYPE`` value or an empty string.
    """
    return UCD1_TO_CTYPE.get(ucd, "")


[docs]class CoordinateFrame: """ Base class for Coordinate Frames. Parameters ---------- naxes : int Number of axes. axes_type : str One of ["SPATIAL", "SPECTRAL", "TIME"] axes_order : tuple of int A dimension in the input data that corresponds to this axis. reference_frame : astropy.coordinates.builtin_frames Reference frame (usually used with output_frame to convert to world coordinate objects). reference_position : str Reference position - one of `STANDARD_REFERENCE_POSITION` unit : list of astropy.units.Unit Unit for each axis. axes_names : list Names of the axes in this frame. name : str Name of this frame. """ def __init__(self, naxes, axes_type, axes_order, reference_frame=None, reference_position=None, unit=None, axes_names=None, name=None, axis_physical_types=None): self._naxes = naxes self._axes_order = tuple(axes_order) if isinstance(axes_type, str): self._axes_type = (axes_type,) else: self._axes_type = tuple(axes_type) self._reference_frame = reference_frame if unit is not None: if astutil.isiterable(unit): unit = tuple(unit) else: unit = (unit,) if len(unit) != naxes: raise ValueError("Number of units does not match number of axes.") else: self._unit = tuple([u.Unit(au) for au in unit]) else: self._unit = tuple(u.Unit("") for na in range(naxes)) if axes_names is not None: if isinstance(axes_names, str): axes_names = (axes_names,) else: axes_names = tuple(axes_names) if len(axes_names) != naxes: raise ValueError("Number of axes names does not match number of axes.") else: axes_names = tuple([""] * naxes) self._axes_names = axes_names if name is None: self._name = self.__class__.__name__ else: self._name = name self._reference_position = reference_position if len(self._axes_type) != naxes: raise ValueError("Length of axes_type does not match number of axes.") if len(self._axes_order) != naxes: raise ValueError("Length of axes_order does not match number of axes.") super(CoordinateFrame, self).__init__() self._axis_physical_types = self._set_axis_physical_types(axis_physical_types) def _set_axis_physical_types(self, pht=None): """ Set the physical type of the coordinate axes using VO UCD1+ v1.23 definitions. """ if pht is not None: if isinstance(pht, str): pht = (pht,) elif not isiterable(pht): raise TypeError("axis_physical_types must be of type string or iterable of strings") if len(pht) != self.naxes: raise ValueError('"axis_physical_types" must be of length {}'.format(self.naxes)) ph_type = [] for axt in pht: if axt not in VALID_UCDS and not axt.startswith("custom:"): ph_type.append("custom:{}".format(axt)) else: ph_type.append(axt) elif isinstance(self, CelestialFrame): if isinstance(self.reference_frame, coord.Galactic): ph_type = "pos.galactic.lon", "pos.galactic.lat" elif isinstance(self.reference_frame, (coord.GeocentricTrueEcliptic, coord.GCRS, coord.PrecessedGeocentric)): ph_type = "pos.bodyrc.lon", "pos.bodyrc.lat" elif isinstance(self.reference_frame, coord.builtin_frames.BaseRADecFrame): ph_type = "pos.eq.ra", "pos.eq.dec" elif isinstance(self.reference_frame, coord.builtin_frames.BaseEclipticFrame): ph_type = "pos.ecliptic.lon", "pos.ecliptic.lat" else: ph_type = tuple("custom:{}".format(t) for t in self.axes_names) elif isinstance(self, SpectralFrame): if self.unit[0].physical_type == "frequency": ph_type = ("em.freq",) elif self.unit[0].physical_type == "length": ph_type = ("em.wl",) elif self.unit[0].physical_type == "energy": ph_type = ("em.energy",) elif self.unit[0].physical_type == "speed": ph_type = ("spect.dopplerVeloc",) logging.warning("Physical type may be ambiguous. Consider " "setting the physical type explicitly as " "either 'spect.dopplerVeloc.optical' or " "'spect.dopplerVeloc.radio'.") else: ph_type = ("custom:{}".format(self.unit[0].physical_type),) elif isinstance(self, TemporalFrame): ph_type = ("time",) elif isinstance(self, Frame2D): if all(self.axes_names): ph_type = self.axes_names else: ph_type = self.axes_type ph_type = tuple("custom:{}".format(t) for t in ph_type) else: ph_type = tuple("custom:{}".format(t) for t in self.axes_type) validate_physical_types(ph_type) return tuple(ph_type) def __repr__(self): fmt = '<{0}(name="{1}", unit={2}, axes_names={3}, axes_order={4}'.format( self.__class__.__name__, self.name, self.unit, self.axes_names, self.axes_order) if self.reference_position is not None: fmt += ', reference_position="{0}"'.format(self.reference_position) if self.reference_frame is not None: fmt += ", reference_frame={0}".format(self.reference_frame) fmt += ")>" return fmt def __str__(self): if self._name is not None: return self._name return self.__class__.__name__ @property def name(self): """ A custom name of this frame.""" return self._name @name.setter def name(self, val): """ A custom name of this frame.""" self._name = val @property def naxes(self): """ The number of axes in this frame.""" return self._naxes @property def unit(self): """The unit of this frame.""" return self._unit @property def axes_names(self): """ Names of axes in the frame.""" return self._axes_names @property def axes_order(self): """ A tuple of indices which map inputs to axes.""" return self._axes_order @property def reference_frame(self): """ Reference frame, used to convert to world coordinate objects. """ return self._reference_frame @property def reference_position(self): """ Reference Position. """ return getattr(self, "_reference_position", None) @property def axes_type(self): """ Type of this frame : 'SPATIAL', 'SPECTRAL', 'TIME'. """ return self._axes_type
[docs] def coordinates(self, *args): """ Create world coordinates object""" coo = tuple([arg * un if not hasattr(arg, "to") else arg.to(un) for arg, un in zip(args, self.unit)]) return coo
[docs] def coordinate_to_quantity(self, *coords): """ Given a rich coordinate object return an astropy quantity object. """ # NoOp leaves it to the model to handle # If coords is a 1-tuple of quantity then return the element of the tuple # This aligns the behavior with the other implementations if not hasattr(coords, 'unit') and len(coords) == 1: return coords[0] return coords
@property def axis_physical_types(self): return self._axis_physical_types @property def _world_axis_object_classes(self): return {self._axes_type[0]: ( u.Quantity, (), {'unit': self.unit[0]})} @property def _world_axis_object_components(self): return [(self._axes_type[0], 0, 'value')]
[docs]class CelestialFrame(CoordinateFrame): """ Celestial Frame Representation Parameters ---------- axes_order : tuple of int A dimension in the input data that corresponds to this axis. reference_frame : astropy.coordinates.builtin_frames A reference frame. unit : str or units.Unit instance or iterable of those Units on axes. axes_names : list Names of the axes in this frame. name : str Name of this frame. """ def __init__(self, axes_order=None, reference_frame=None, unit=None, axes_names=None, name=None, axis_physical_types=None): naxes = 2 if reference_frame is not None: if not isinstance(reference_frame, str): if reference_frame.name.upper() in STANDARD_REFERENCE_FRAMES: _axes_names = list(reference_frame.representation_component_names.values()) if 'distance' in _axes_names: _axes_names.remove('distance') if axes_names is None: axes_names = _axes_names naxes = len(_axes_names) _unit = list(reference_frame.representation_component_units.values()) if unit is None and _unit: unit = _unit if axes_order is None: axes_order = tuple(range(naxes)) if unit is None: unit = tuple([u.degree] * naxes) axes_type = ['SPATIAL'] * naxes super(CelestialFrame, self).__init__(naxes=naxes, axes_type=axes_type, axes_order=axes_order, reference_frame=reference_frame, unit=unit, axes_names=axes_names, name=name, axis_physical_types=axis_physical_types) @property def _world_axis_object_classes(self): return {'celestial': ( coord.SkyCoord, (), {'frame': self.reference_frame, 'unit': self.unit})} @property def _world_axis_object_components(self): return [('celestial', 0, 'spherical.lon'), ('celestial', 1, 'spherical.lat')]
[docs] def coordinates(self, *args): """ Create a SkyCoord object. Parameters ---------- args : float inputs to wcs.input_frame """ if isinstance(args[0], coord.SkyCoord): return args[0].transform_to(self.reference_frame) return coord.SkyCoord(*args, unit=self.unit, frame=self.reference_frame)
[docs] def coordinate_to_quantity(self, *coords): """ Convert a ``SkyCoord`` object to quantities.""" if len(coords) == 2: arg = coords elif len(coords) == 1: arg = coords[0] else: raise ValueError("Unexpected number of coordinates in " "input to frame {} : " "expected 2, got {}".format(self.name, len(coords))) if isinstance(arg, coord.SkyCoord): arg = arg.transform_to(self._reference_frame) try: lon = arg.data.lon lat = arg.data.lat except AttributeError: lon = arg.spherical.lon lat = arg.spherical.lat return lon, lat elif all(isinstance(a, u.Quantity) for a in arg): return tuple(arg) else: raise ValueError("Could not convert input {} to lon and lat quantities.".format(arg))
[docs]class SpectralFrame(CoordinateFrame): """ Represents Spectral Frame Parameters ---------- axes_order : tuple or int A dimension in the input data that corresponds to this axis. reference_frame : astropy.coordinates.builtin_frames Reference frame (usually used with output_frame to convert to world coordinate objects). unit : str or units.Unit instance Spectral unit. axes_names : str Spectral axis name. name : str Name for this frame. reference_position : str Reference position - one of `STANDARD_REFERENCE_POSITION` """ def __init__(self, axes_order=(0,), reference_frame=None, unit=None, axes_names=None, name=None, axis_physical_types=None, reference_position=None): super(SpectralFrame, self).__init__(naxes=1, axes_type="SPECTRAL", axes_order=axes_order, axes_names=axes_names, reference_frame=reference_frame, unit=unit, name=name, reference_position=reference_position, axis_physical_types=axis_physical_types) @property def _world_axis_object_classes(self): return {'spectral': ( u.Quantity, (), {'unit': self.unit[0]})} @property def _world_axis_object_components(self): return [('spectral', 0, 'value')]
[docs] def coordinates(self, *args, equivalencies=[]): if hasattr(args[0], 'unit'): return args[0].to(self.unit[0], equivalencies=equivalencies) if np.isscalar(args): return args * self.unit[0] else: return args[0] * self.unit[0]
[docs] def coordinate_to_quantity(self, *coords): if hasattr(coords[0], 'unit'): return coords[0] return coords[0] * self.unit[0]
[docs]class TemporalFrame(CoordinateFrame): """ A coordinate frame for time axes. Parameters ---------- reference_frame : `~astropy.time.Time` A Time object which holds the time scale and format. If data is provided, it is the time zero point. To not set a zero point for the frame initialize `reference_frame` with an empty list. unit : str or `~astropy.units.Unit` Time unit. axes_names : str Time axis name. axes_order : tuple or int A dimension in the data that corresponds to this axis. name : str Name for this frame. """ def __init__(self, reference_frame, unit=None, axes_order=(0,), axes_names=None, name=None, axis_physical_types=None): axes_names = axes_names or "{}({}; {}".format(reference_frame.format, reference_frame.scale, reference_frame.location) super().__init__(naxes=1, axes_type="TIME", axes_order=axes_order, axes_names=axes_names, reference_frame=reference_frame, unit=unit, name=name, axis_physical_types=axis_physical_types) self._attrs = {} for a in self.reference_frame.info._represent_as_dict_extra_attrs: try: self._attrs[a] = getattr(self.reference_frame, a) except AttributeError: pass @property def _world_axis_object_classes(self): comp = ( time.Time, (), {'unit': self.unit[0], **self._attrs}, self._convert_to_time) return {'temporal': comp} @property def _world_axis_object_components(self): if isinstance(self.reference_frame.value, np.ndarray): return [('temporal', 0, 'value')] def offset_from_time_and_reference(time): return (time - self.reference_frame).sec return [('temporal', 0, offset_from_time_and_reference)]
[docs] def coordinates(self, *args): if np.isscalar(args): dt = args else: dt = args[0] return self._convert_to_time(dt, unit=self.unit[0], **self._attrs)
def _convert_to_time(self, dt, *, unit, **kwargs): if (not isinstance(dt, time.TimeDelta) and isinstance(dt, time.Time) or isinstance(self.reference_frame.value, np.ndarray)): return time.Time(dt, **kwargs) if not hasattr(dt, 'unit'): dt = dt * unit return self.reference_frame + dt
[docs] def coordinate_to_quantity(self, *coords): if isinstance(coords[0], time.Time): ref_value = self.reference_frame.value if not isinstance(ref_value, np.ndarray): return (coords[0] - self.reference_frame).to(self.unit[0]) else: # If we can't convert to a quantity just drop the object out # and hope the transform can cope. return coords[0] # Is already a quantity elif hasattr(coords[0], 'unit'): return coords[0] if isinstance(coords[0], np.ndarray): return coords[0] * self.unit[0] else: raise ValueError("Can not convert {} to Quantity".format(coords[0]))
[docs]class CompositeFrame(CoordinateFrame): """ Represents one or more frames. Parameters ---------- frames : list List of frames (TemporalFrame, CelestialFrame, SpectralFrame, CoordinateFrame). name : str Name for this frame. """ def __init__(self, frames, name=None): self._frames = frames[:] naxes = sum([frame._naxes for frame in self._frames]) axes_type = list(range(naxes)) unit = list(range(naxes)) axes_names = list(range(naxes)) axes_order = [] ph_type = list(range(naxes)) for frame in frames: axes_order.extend(frame.axes_order) for frame in frames: for ind, axtype, un, n, pht in zip(frame.axes_order, frame.axes_type, frame.unit, frame.axes_names, frame.axis_physical_types): axes_type[ind] = axtype axes_names[ind] = n unit[ind] = un ph_type[ind] = pht if len(np.unique(axes_order)) != len(axes_order): raise ValueError("Incorrect numbering of axes, " "axes_order should contain unique numbers, " "got {}.".format(axes_order)) super(CompositeFrame, self).__init__(naxes, axes_type=axes_type, axes_order=axes_order, unit=unit, axes_names=axes_names, name=name) self._axis_physical_types = tuple(ph_type) @property def frames(self): return self._frames def __repr__(self): return repr(self.frames)
[docs] def coordinates(self, *args): coo = [] if len(args) == len(self.frames): for frame, arg in zip(self.frames, args): coo.append(frame.coordinates(arg)) else: for frame in self.frames: fargs = [args[i] for i in frame.axes_order] coo.append(frame.coordinates(*fargs)) return coo
[docs] def coordinate_to_quantity(self, *coords): if len(coords) == len(self.frames): args = coords elif len(coords) == self.naxes: args = [] for _frame in self.frames: if _frame.naxes > 1: # Collect the arguments for this frame based on axes_order args.append([coords[i] for i in _frame.axes_order]) else: args.append(coords[_frame.axes_order[0]]) else: raise ValueError("Incorrect number of arguments") qs = [] for _frame, arg in zip(self.frames, args): ret = _frame.coordinate_to_quantity(arg) if isinstance(ret, tuple): qs += list(ret) else: qs.append(ret) return qs
@property def _world_axis_object_components(self): """ We need to generate the components respecting the axes_order. """ out = [None] * self.naxes for frame in self.frames: for i, ao in enumerate(frame.axes_order): out[ao] = frame._world_axis_object_components[i] if any([o is None for o in out]): raise ValueError("axes_order leads to incomplete world_axis_object_components") return out @property def _world_axis_object_classes(self): out = {} for frame in self.frames: out.update(frame._world_axis_object_classes) return out
class StokesProfile(str): # This list of profiles in Table 7 in Greisen & Calabretta (2002) # modified to be 0 indexed profiles = { 'I': 0, 'Q': 1, 'U': 2, 'V': 3, 'RR': -1, 'LL': -2, 'RL': -3, 'LR': -4, 'XX': -5, 'YY': -6, 'XY': -7, 'YX': -8, } @classmethod def from_index(cls, indexes): """ Construct a StokesProfile object from a numerical index. Parameters ---------- indexes : `int`, `numpy.ndarray` An index or array of indices to construct StokesProfile objects from. """ nans = np.isnan(indexes) indexes = np.asanyarray(indexes, dtype=int) out = np.empty_like(indexes, dtype=object) for profile, index in cls.profiles.items(): out[indexes == index] = profile out[nans] = np.nan if out.size == 1 and not nans: return StokesProfile(out.item()) elif nans.all(): return np.array(out, dtype=float) return out def __new__(cls, content): content = str(content) if content not in cls.profiles.keys(): raise ValueError(f"The profile name must be one of {cls.profiles.keys()} not {content}") return str.__new__(cls, content) def value(self): return self.profiles[self] class StokesFrame(CoordinateFrame): """ A coordinate frame for representing stokes polarisation states Parameters ---------- name : str Name of this frame. """ def __init__(self, axes_order=(0,), name=None): super(StokesFrame, self).__init__(1, ["STOKES"], axes_order, name=name, axes_names=("stokes",), unit=u.one, axis_physical_types="phys.polarization.stokes") @property def _world_axis_object_classes(self): return {'stokes': ( StokesProfile, (), {}, StokesProfile.from_index)} @property def _world_axis_object_components(self): return [('stokes', 0, 'value')] def coordinates(self, *args): if isinstance(args[0], u.Quantity): arg = args[0].value else: arg = args[0] return StokesProfile.from_index(arg) def coordinate_to_quantity(self, *coords): if isinstance(coords[0], str): if coords[0] in StokesProfile.profiles.keys(): return StokesProfile.profiles[coords[0]] * u.one else: return coords[0]
[docs]class Frame2D(CoordinateFrame): """ A 2D coordinate frame. Parameters ---------- axes_order : tuple of int A dimension in the input data that corresponds to this axis. unit : list of astropy.units.Unit Unit for each axis. axes_names : list Names of the axes in this frame. name : str Name of this frame. """ def __init__(self, axes_order=(0, 1), unit=(u.pix, u.pix), axes_names=('x', 'y'), name=None, axis_physical_types=None): super(Frame2D, self).__init__(naxes=2, axes_type=["SPATIAL", "SPATIAL"], axes_order=axes_order, name=name, axes_names=axes_names, unit=unit, axis_physical_types=axis_physical_types)
[docs] def coordinates(self, *args): args = [args[i] for i in self.axes_order] coo = tuple([arg * un for arg, un in zip(args, self.unit)]) return coo
[docs] def coordinate_to_quantity(self, *coords): # list or tuple if len(coords) == 1 and astutil.isiterable(coords[0]): coords = list(coords[0]) elif len(coords) == 2: coords = list(coords) else: raise ValueError("Unexpected number of coordinates in " "input to frame {} : " "expected 2, got {}".format(self.name, len(coords))) for i in range(2): if not hasattr(coords[i], 'unit'): coords[i] = coords[i] * self.unit[i] return tuple(coords)