from __future__ import (absolute_import, division, print_function, unicode_literals) import re import collections import warnings import numpy as np from ..utils.compat.misc import override__dir__ from ..extern import six from ..extern.six.moves import zip, range from ..units import Unit, IrreducibleUnit from .. import units as u from ..wcs.utils import skycoord_to_pixel, pixel_to_skycoord from ..utils.exceptions import AstropyDeprecationWarning from ..utils.data_info import MixinInfo, _get_obj_attrs_map from ..utils import ShapedLikeNDArray from .distances import Distance from .angles import Angle from .baseframe import BaseCoordinateFrame, frame_transform_graph, GenericFrame, _get_repr_cls from .builtin_frames import ICRS, SkyOffsetFrame from .representation import (BaseRepresentation, SphericalRepresentation, UnitSphericalRepresentation) __all__ = ['SkyCoord'] PLUS_MINUS_RE = re.compile(r'(\+|\-)') J_PREFIXED_RA_DEC_RE = re.compile( r"""J # J prefix ([0-9]{6,7}\.?[0-9]{0,2}) # RA as HHMMSS.ss or DDDMMSS.ss, optional decimal digits ([\+\-][0-9]{6}\.?[0-9]{0,2})\s*$ # Dec as DDMMSS.ss, optional decimal digits """, re.VERBOSE) # Define a convenience mapping. This is used like a module constants # but is actually dynamically evaluated. def FRAME_ATTR_NAMES_SET(): """Set of all possible frame-specific attributes""" out = set() for frame_cls in frame_transform_graph.frame_set: for attr in frame_cls.get_frame_attr_names().keys(): out.add(attr) return out class SkyCoordInfo(MixinInfo): """ Container for meta information like name, description, format. This is required when the object is used as a mixin column within a table, but can be used as a general way to store meta information. """ attrs_from_parent = set(['unit']) # Unit is read-only _supports_indexing = False @staticmethod def default_format(val): repr_data = val.info._repr_data formats = ['{0.' + compname + '.value:}' for compname in repr_data.components] return ','.join(formats).format(repr_data) @property def unit(self): repr_data = self._repr_data unit = ','.join(str(getattr(repr_data, comp).unit) or 'None' for comp in repr_data.components) return unit @property def _repr_data(self): if self._parent is None: return None sc = self._parent if (issubclass(sc.representation, SphericalRepresentation) and isinstance(sc.data, UnitSphericalRepresentation)): repr_data = sc.represent_as(sc.data.__class__, in_frame_units=True) else: repr_data = sc.represent_as(sc.representation, in_frame_units=True) return repr_data def _represent_as_dict(self): obj = self._parent attrs = list(obj.representation_component_names) attrs += list(FRAME_ATTR_NAMES_SET()) out = _get_obj_attrs_map(obj, attrs) # Don't output distance if it is all unitless 1.0 if 'distance' in out and np.all(out['distance'] == 1.0): del out['distance'] out['representation'] = obj.representation.get_name() out['frame'] = obj.frame.name return out class SkyCoord(ShapedLikeNDArray): """High-level object providing a flexible interface for celestial coordinate representation, manipulation, and transformation between systems. The `SkyCoord` class accepts a wide variety of inputs for initialization. At a minimum these must provide one or more celestial coordinate values with unambiguous units. Inputs may be scalars or lists/tuples/arrays, yielding scalar or array coordinates (can be checked via ``SkyCoord.isscalar``). Typically one also specifies the coordinate frame, though this is not required. The general pattern for spherical representations is:: SkyCoord(COORD, [FRAME], keyword_args ...) SkyCoord(LON, LAT, [FRAME], keyword_args ...) SkyCoord(LON, LAT, [DISTANCE], frame=FRAME, unit=UNIT, keyword_args ...) SkyCoord([FRAME], =LON, =LAT, keyword_args ...) It is also possible to input coordinate values in other representations such as cartesian or cylindrical. In this case one includes the keyword argument ``representation='cartesian'`` (for example) along with data in ``x``, ``y``, and ``z``. Examples -------- The examples below illustrate common ways of initializing a `SkyCoord` object. For a complete description of the allowed syntax see the full coordinates documentation. First some imports:: >>> from astropy.coordinates import SkyCoord # High-level coordinates >>> from astropy.coordinates import ICRS, Galactic, FK4, FK5 # Low-level frames >>> from astropy.coordinates import Angle, Latitude, Longitude # Angles >>> import astropy.units as u The coordinate values and frame specification can now be provided using positional and keyword arguments:: >>> c = SkyCoord(10, 20, unit="deg") # defaults to ICRS frame >>> c = SkyCoord([1, 2, 3], [-30, 45, 8], "icrs", unit="deg") # 3 coords >>> coords = ["1:12:43.2 +1:12:43", "1 12 43.2 +1 12 43"] >>> c = SkyCoord(coords, FK4, unit=(u.deg, u.hourangle), obstime="J1992.21") >>> c = SkyCoord("1h12m43.2s +1d12m43s", Galactic) # Units from string >>> c = SkyCoord("galactic", l="1h12m43.2s", b="+1d12m43s") >>> ra = Longitude([1, 2, 3], unit=u.deg) # Could also use Angle >>> dec = np.array([4.5, 5.2, 6.3]) * u.deg # Astropy Quantity >>> c = SkyCoord(ra, dec, frame='icrs') >>> c = SkyCoord(ICRS, ra=ra, dec=dec, obstime='2001-01-02T12:34:56') >>> c = FK4(1 * u.deg, 2 * u.deg) # Uses defaults for obstime, equinox >>> c = SkyCoord(c, obstime='J2010.11', equinox='B1965') # Override defaults >>> c = SkyCoord(w=0, u=1, v=2, unit='kpc', frame='galactic', representation='cartesian') >>> c = SkyCoord([ICRS(ra=1*u.deg, dec=2*u.deg), ICRS(ra=3*u.deg, dec=4*u.deg)]) As shown, the frame can be a `~astropy.coordinates.BaseCoordinateFrame` class or the corresponding string alias. The frame classes that are built in to astropy are `ICRS`, `FK5`, `FK4`, `FK4NoETerms`, and `Galactic`. The string aliases are simply lower-case versions of the class name, and allow for creating a `SkyCoord` object and transforming frames without explicitly importing the frame classes. Parameters ---------- frame : `~astropy.coordinates.BaseCoordinateFrame` class or string, optional Type of coordinate frame this `SkyCoord` should represent. Defaults to to ICRS if not given or given as None. unit : `~astropy.units.Unit`, string, or tuple of :class:`~astropy.units.Unit` or str, optional Units for supplied ``LON`` and ``LAT`` values, respectively. If only one unit is supplied then it applies to both ``LON`` and ``LAT``. obstime : valid `~astropy.time.Time` initializer, optional Time of observation equinox : valid `~astropy.time.Time` initializer, optional Coordinate frame equinox representation : str or Representation class Specifies the representation, e.g. 'spherical', 'cartesian', or 'cylindrical'. This affects the positional args and other keyword args which must correspond to the given representation. copy : bool, optional If `True` (default), a copy of any coordinate data is made. This argument can only be passed in as a keyword argument. **keyword_args Other keyword arguments as applicable for user-defined coordinate frames. Common options include: ra, dec : valid `~astropy.coordinates.Angle` initializer, optional RA and Dec for frames where ``ra`` and ``dec`` are keys in the frame's ``representation_component_names``, including `ICRS`, `FK5`, `FK4`, and `FK4NoETerms`. l, b : valid `~astropy.coordinates.Angle` initializer, optional Galactic ``l`` and ``b`` for for frames where ``l`` and ``b`` are keys in the frame's ``representation_component_names``, including the `Galactic` frame. x, y, z : float or `~astropy.units.Quantity`, optional Cartesian coordinates values w, u, v : float or `~astropy.units.Quantity`, optional Cartesian coordinates values for the Galactic frame. """ # Declare that SkyCoord can be used as a Table column by defining the # info property. info = SkyCoordInfo() def __init__(self, *args, **kwargs): # Parse the args and kwargs to assemble a sanitized and validated # kwargs dict for initializing attributes for this object and for # creating the internal self._sky_coord_frame object args = list(args) # Make it mutable copy = kwargs.pop('copy', True) kwargs = self._parse_inputs(args, kwargs) # Set internal versions of object state attributes for attr in FRAME_ATTR_NAMES_SET(): setattr(self, '_' + attr, kwargs[attr]) frame = kwargs['frame'] coord_kwargs = {} if 'representation' in kwargs: coord_kwargs['representation'] = _get_repr_cls(kwargs['representation']) for attr, value in kwargs.items(): if value is not None and (attr in frame.representation_component_names or attr in frame.get_frame_attr_names()): coord_kwargs[attr] = value # Finally make the internal coordinate object. self._sky_coord_frame = frame.__class__(copy=copy, **coord_kwargs) if not self._sky_coord_frame.has_data: raise ValueError('Cannot create a SkyCoord without data') @property def frame(self): return self._sky_coord_frame @property def representation(self): return self.frame.representation @representation.setter def representation(self, value): self.frame.representation = value @property def shape(self): return self.frame.shape def _apply(self, method, *args, **kwargs): """Create a new instance, applying a method to the underlying data. In typical usage, the method is any of the shape-changing methods for `~numpy.ndarray` (``reshape``, ``swapaxes``, etc.), as well as those picking particular elements (``__getitem__``, ``take``, etc.), which are all defined in `~astropy.utils.misc.ShapedLikeNDArray`. It will be applied to the underlying arrays in the representation (e.g., ``x``, ``y``, and ``z`` for `~astropy.coordinates.CartesianRepresentation`), as well as to any frame attributes that have a shape, with the results used to create a new instance. Internally, it is also used to apply functions to the above parts (in particular, `~numpy.broadcast_to`). Parameters ---------- method : str or callable If str, it is the name of a method that is applied to the internal ``components``. If callable, the function is applied. args : tuple Any positional arguments for ``method``. kwargs : dict Any keyword arguments for ``method``. """ self_frame = self._sky_coord_frame try: # First turn `self` into a mockup of the thing we want - we can copy # this to get all the right attributes self._sky_coord_frame = self_frame._apply(method, *args, **kwargs) out = SkyCoord(self, representation=self.representation, copy=False) # Copy other 'info' attr only if it has actually been defined. # See PR #3898 for further explanation and justification, along # with Quantity.__array_finalize__ if 'info' in self.__dict__: out.info = self.info return out finally: # now put back the right frame in self self._sky_coord_frame = self_frame def _parse_inputs(self, args, kwargs): """ Assemble a validated and sanitized keyword args dict for instantiating a SkyCoord and coordinate object from the provided `args`, and `kwargs`. """ valid_kwargs = {} # Put the SkyCoord attributes like frame, equinox, obstime, location # into valid_kwargs dict. `Frame` could come from args or kwargs, so # set valid_kwargs['frame'] accordingly. The others must be specified # by keyword args or else get a None default. Pop them off of kwargs # in the process. frame = valid_kwargs['frame'] = _get_frame(args, kwargs) if 'representation' in kwargs: valid_kwargs['representation'] = _get_repr_cls(kwargs.pop('representation')) for attr in FRAME_ATTR_NAMES_SET(): valid_kwargs[attr] = kwargs.pop(attr, None) # Get units units = _get_units(args, kwargs) # Grab any frame-specific attr names like `ra` or `l` or `distance` from kwargs # and migrate to valid_kwargs. valid_kwargs.update(_get_representation_attrs(frame, units, kwargs)) # Error if anything is still left in kwargs if kwargs: raise ValueError('Unrecognized keyword argument(s) {0}' .format(', '.join("'{0}'".format(key) for key in kwargs))) # Finally deal with the unnamed args. This figures out what the arg[0] is # and returns a dict with appropriate key/values for initializing frame class. if args: if len(args) == 1: # One arg which must be a coordinate. In this case # coord_kwargs will contain keys like 'ra', 'dec', 'distance' # along with any frame attributes like equinox or obstime which # were explicitly specified in the coordinate object (i.e. non-default). coord_kwargs = _parse_coordinate_arg(args[0], frame, units, kwargs) # Copy other 'info' attr only if it has actually been defined. if 'info' in getattr(args[0], '__dict__', ()): self.info = args[0].info elif len(args) <= 3: frame_attr_names = frame.representation_component_names.keys() repr_attr_names = frame.representation_component_names.values() coord_kwargs = {} for arg, frame_attr_name, repr_attr_name, unit in zip(args, frame_attr_names, repr_attr_names, units): attr_class = frame.representation.attr_classes[repr_attr_name] coord_kwargs[frame_attr_name] = attr_class(arg, unit=unit) else: raise ValueError('Must supply no more than three positional arguments, got {}' .format(len(args))) # Copy the coord_kwargs into the final valid_kwargs dict. For each # of the coord_kwargs ensure that there is no conflict with a value # specified by the user in the original kwargs. for attr, coord_value in coord_kwargs.items(): if (attr in valid_kwargs and valid_kwargs[attr] is not None and np.any(valid_kwargs[attr] != coord_value)): raise ValueError("Coordinate attribute '{0}'={1!r} conflicts with " "keyword argument '{0}'={2!r}" .format(attr, coord_value, valid_kwargs[attr])) valid_kwargs[attr] = coord_value return valid_kwargs def transform_to(self, frame): """ Transform this coordinate to a new frame. The frame attributes (e.g. equinox or obstime) for the returned object depend on the corresponding attributes of SkyCoord object and the supplied ``frame``, with the following precedence: 1. Non-default value in the supplied frame 2. Non-default value in the SkyCoord instance 3. Default value in the supplied frame Parameters ---------- frame : str or `BaseCoordinateFrame` class / instance or `SkyCoord` instance The frame to transform this coordinate into. Returns ------- coord : `SkyCoord` A new object with this coordinate represented in the `frame` frame. Raises ------ ValueError If there is no possible transformation route. """ from astropy.coordinates.errors import ConvertError frame_kwargs = {} # Frame name (string) or frame class? Coerce into an instance. try: frame = _get_frame_class(frame)() except Exception: pass if isinstance(frame, SkyCoord): frame = frame.frame # Change to underlying coord frame instance if isinstance(frame, BaseCoordinateFrame): new_frame_cls = frame.__class__ # Set the keyword args for making a new frame instance for the # transform. Frame attributes track whether they were explicitly # set by user or are just reflecting default values. Precedence: # 1. Non-default value in the supplied frame instance # 2. Non-default value in the self instance # 3. Default value in the supplied frame instance for attr in FRAME_ATTR_NAMES_SET(): self_val = getattr(self, attr, None) frame_val = getattr(frame, attr, None) if frame_val is not None and not frame.is_frame_attr_default(attr): frame_kwargs[attr] = frame_val elif self_val is not None and not self.is_frame_attr_default(attr): frame_kwargs[attr] = self_val elif frame_val is not None: frame_kwargs[attr] = frame_val else: raise ValueError('Transform `frame` must be a frame name, class, or instance') # Get the composite transform to the new frame trans = frame_transform_graph.get_transform(self.frame.__class__, new_frame_cls) if trans is None: raise ConvertError('Cannot transform from {0} to {1}' .format(self.frame.__class__, new_frame_cls)) # Make a generic frame which will accept all the frame kwargs that # are provided and allow for transforming through intermediate frames # which may require one or more of those kwargs. generic_frame = GenericFrame(frame_kwargs) # Do the transformation, returning a coordinate frame of the desired # final type (not generic). new_coord = trans(self.frame, generic_frame) # Finally make the new SkyCoord object from the `new_coord` and # remaining frame_kwargs that are not frame_attributes in `new_coord`. # We could remove overlaps here, but the init code is set up to accept # overlaps as long as the values are identical (which they must be). return self.__class__(new_coord, **frame_kwargs) def __getattr__(self, attr): """ Overrides getattr to return coordinates that this can be transformed to, based on the alias attr in the master transform graph. """ if '_sky_coord_frame' in self.__dict__: if self.frame.name == attr: return self # Should this be a deepcopy of self? # Anything in the set of all possible frame_attr_names is handled # here. If the attr is relevant for the current frame then delegate # to self.frame otherwise get it from self._. if attr in FRAME_ATTR_NAMES_SET(): if attr in self.frame.get_frame_attr_names(): return getattr(self.frame, attr) else: try: return getattr(self, '_' + attr) except AttributeError: # this can happen because FRAME_ATTR_NAMES_SET is # dynamic. So if a frame is added to the transform # graph after this SkyCoord was created, the "real" # underlying attribute - e.g. `_equinox` does not exist # on the SkyCoord. So we add this case to just use # None, as it wouldn't have been possible for the user # to have set the value until the frame existed anyway return None # Some attributes might not fall in the above category but still # are available through self._sky_coord_frame. if not attr.startswith('_') and hasattr(self._sky_coord_frame, attr): return getattr(self._sky_coord_frame, attr) # Try to interpret as a new frame for transforming. frame_cls = frame_transform_graph.lookup_name(attr) if frame_cls is not None and self.frame.is_transformable_to(frame_cls): return self.transform_to(attr) # Fail raise AttributeError("'{0}' object has no attribute '{1}'" .format(self.__class__.__name__, attr)) def __setattr__(self, attr, val): # This is to make anything available through __getattr__ immutable if '_sky_coord_frame' in self.__dict__: if self.frame.name == attr: raise AttributeError("'{0}' is immutable".format(attr)) if (attr in FRAME_ATTR_NAMES_SET() or (not attr.startswith('_') and hasattr(self._sky_coord_frame, attr))): setattr(self._sky_coord_frame, attr, val) frame_cls = frame_transform_graph.lookup_name(attr) if frame_cls is not None and self.frame.is_transformable_to(frame_cls): raise AttributeError("'{0}' is immutable".format(attr)) # Otherwise, do the standard Python attribute setting super(SkyCoord, self).__setattr__(attr, val) @override__dir__ def __dir__(self): """ Override the builtin `dir` behavior to include: - Transforms available by aliases - Attribute / methods of the underlying self.frame object """ # determine the aliases that this can be transformed to. dir_values = set() for name in frame_transform_graph.get_names(): frame_cls = frame_transform_graph.lookup_name(name) if self.frame.is_transformable_to(frame_cls): dir_values.add(name) # Add public attributes of self.frame dir_values.update(set(attr for attr in dir(self.frame) if not attr.startswith('_'))) # Add all possible frame attributes dir_values.update(FRAME_ATTR_NAMES_SET()) return dir_values def __repr__(self): clsnm = self.__class__.__name__ coonm = self.frame.__class__.__name__ frameattrs = self.frame._frame_attrs_repr() if frameattrs: frameattrs = ': ' + frameattrs data = self.frame._data_repr() if data: data = ': ' + data return '<{clsnm} ({coonm}{frameattrs}){data}>'.format(**locals()) def to_string(self, style='decimal', **kwargs): """ A string representation of the coordinates. The default styles definitions are:: 'decimal': 'lat': {'decimal': True, 'unit': "deg"} 'lon': {'decimal': True, 'unit': "deg"} 'dms': 'lat': {'unit': "deg"} 'lon': {'unit': "deg"} 'hmsdms': 'lat': {'alwayssign': True, 'pad': True, 'unit': "deg"} 'lon': {'pad': True, 'unit': "hour"} See :meth:`~astropy.coordinates.Angle.to_string` for details and keyword arguments (the two angles forming the coordinates are are both :class:`~astropy.coordinates.Angle` instances). Keyword arguments have precedence over the style defaults and are passed to :meth:`~astropy.coordinates.Angle.to_string`. Parameters ---------- style : {'hmsdms', 'dms', 'decimal'} The formatting specification to use. These encode the three most common ways to represent coordinates. The default is `decimal`. kwargs Keyword args passed to :meth:`~astropy.coordinates.Angle.to_string`. """ sph_coord = self.frame.represent_as(SphericalRepresentation) styles = {'hmsdms': {'lonargs': {'unit': u.hour, 'pad': True}, 'latargs': {'unit': u.degree, 'pad': True, 'alwayssign': True}}, 'dms': {'lonargs': {'unit': u.degree}, 'latargs': {'unit': u.degree}}, 'decimal': {'lonargs': {'unit': u.degree, 'decimal': True}, 'latargs': {'unit': u.degree, 'decimal': True}} } lonargs = {} latargs = {} if style in styles: lonargs.update(styles[style]['lonargs']) latargs.update(styles[style]['latargs']) else: raise ValueError('Invalid style. Valid options are: {0}'.format(",".join(styles))) lonargs.update(kwargs) latargs.update(kwargs) if np.isscalar(sph_coord.lon.value): coord_string = (sph_coord.lon.to_string(**lonargs) + " " + sph_coord.lat.to_string(**latargs)) else: coord_string = [] for lonangle, latangle in zip(sph_coord.lon.ravel(), sph_coord.lat.ravel()): coord_string += [(lonangle.to_string(**lonargs) + " " + latangle.to_string(**latargs))] if len(sph_coord.shape) > 1: coord_string = np.array(coord_string).reshape(sph_coord.shape) return coord_string def is_equivalent_frame(self, other): """ Checks if this object's frame as the same as that of the ``other`` object. To be the same frame, two objects must be the same frame class and have the same frame attributes. For two `SkyCoord` objects, *all* of the frame attributes have to match, not just those relevant for the object's frame. Parameters ---------- other : SkyCoord or BaseCoordinateFrame The other object to check. Returns ------- isequiv : bool True if the frames are the same, False if not. Raises ------ TypeError If ``other`` isn't a `SkyCoord` or a `BaseCoordinateFrame` or subclass. """ if isinstance(other, BaseCoordinateFrame): return self.frame.is_equivalent_frame(other) elif isinstance(other, SkyCoord): if other.frame.name != self.frame.name: return False for fattrnm in FRAME_ATTR_NAMES_SET(): if getattr(self, fattrnm) != getattr(other, fattrnm): return False return True else: #not a BaseCoordinateFrame nor a SkyCoord object raise TypeError("Tried to do is_equivalent_frame on something that " "isn't frame-like") # High-level convenience methods def separation(self, other): """ Computes on-sky separation between this coordinate and another. For more on how to use this (and related) functionality, see the examples in :doc:`/coordinates/matchsep`. Parameters ---------- other : `~astropy.coordinates.SkyCoord` or `~astropy.coordinates.BaseCoordinateFrame` The coordinate to get the separation to. Returns ------- sep : `~astropy.coordinates.Angle` The on-sky separation between this and the ``other`` coordinate. Notes ----- The separation is calculated using the Vincenty formula, which is stable at all locations, including poles and antipodes [1]_. .. [1] http://en.wikipedia.org/wiki/Great-circle_distance """ from . import Angle from .angle_utilities import angular_separation if isinstance(other, SkyCoord): self_in_other_system = self.transform_to(other.frame) elif isinstance(other, BaseCoordinateFrame) and other.has_data: # it's a frame self_in_other_system = self.transform_to(other) else: raise TypeError('Can only get separation to another SkyCoord or a ' 'coordinate frame with data') lon1 = self_in_other_system.spherical.lon lat1 = self_in_other_system.spherical.lat lon2 = other.spherical.lon lat2 = other.spherical.lat # Get the separation as a Quantity, convert to Angle in degrees sep = angular_separation(lon1, lat1, lon2, lat2) return Angle(sep, unit=u.degree) def separation_3d(self, other): """ Computes three dimensional separation between this coordinate and another. For more on how to use this (and related) functionality, see the examples in :doc:`/coordinates/matchsep`. Parameters ---------- other : `~astropy.coordinates.SkyCoord` or `~astropy.coordinates.BaseCoordinateFrame` The coordinate to get the separation to. Returns ------- sep : `~astropy.coordinates.Distance` The real-space distance between these two coordinates. Raises ------ ValueError If this or the other coordinate do not have distances. """ if isinstance(other, SkyCoord): self_in_other_system = self.transform_to(other.frame) elif isinstance(other, BaseCoordinateFrame) and other.has_data: # it's a frame self_in_other_system = self.transform_to(other) else: raise TypeError('Can only get separation to another SkyCoord or a ' 'coordinate frame with data') if issubclass(self.data.__class__, UnitSphericalRepresentation): raise ValueError('This object does not have a distance; cannot ' 'compute 3d separation.') if issubclass(other.data.__class__, UnitSphericalRepresentation): raise ValueError('The other object does not have a distance; ' 'cannot compute 3d separation.') return Distance((self_in_other_system.cartesian - other.cartesian).norm()) def spherical_offsets_to(self, tocoord): r""" Computes angular offsets to go *from* this coordinate *to* another. Parameters ---------- tocoord : `~astropy.coordinates.BaseCoordinateFrame` The coordinate to offset to. Returns ------- lon_offset : `~astropy.coordinates.Angle` The angular offset in the longitude direction (i.e., RA for equatorial coordinates). lat_offset : `~astropy.coordinates.Angle` The angular offset in the latitude direction (i.e., Dec for equatorial coordinates). Raises ------ ValueError If the ``tocoord`` is not in the same frame as this one. This is different from the behavior of the `separation`/`separation_3d` methods because the offset components depend critically on the specific choice of frame. Notes ----- This uses the sky offset frame machinery, and hence will produce a new sky offset frame if one does not already exist for this object's frame class. See Also -------- separation : for the *total* angular offset (not broken out into components) """ if not self.is_equivalent_frame(tocoord): raise ValueError('Tried to use spherical_offsets_to with two non-matching frames!') aframe = self.skyoffset_frame() acoord = tocoord.transform_to(aframe) dlon = acoord.spherical.lon.view(Angle) dlat = acoord.spherical.lat.view(Angle) return dlon, dlat def match_to_catalog_sky(self, catalogcoord, nthneighbor=1): """ Finds the nearest on-sky matches of this coordinate in a set of catalog coordinates. For more on how to use this (and related) functionality, see the examples in :doc:`/coordinates/matchsep`. Parameters ---------- catalogcoord : `~astropy.coordinates.SkyCoord` or `~astropy.coordinates.BaseCoordinateFrame` The base catalog in which to search for matches. Typically this will be a coordinate object that is an array (i.e., ``catalogcoord.isscalar == False``) nthneighbor : int, optional Which closest neighbor to search for. Typically ``1`` is desired here, as that is correct for matching one set of coordinates to another. The next likely use case is ``2``, for matching a coordinate catalog against *itself* (``1`` is inappropriate because each point will find itself as the closest match). Returns ------- idx : integer array Indices into ``catalogcoord`` to get the matched points for each of this object's coordinates. Shape matches this object. sep2d : `~astropy.coordinates.Angle` The on-sky separation between the closest match for each element in this object in ``catalogcoord``. Shape matches this object. dist3d : `~astropy.units.Quantity` The 3D distance between the closest match for each element in this object in ``catalogcoord``. Shape matches this object. Notes ----- This method requires `SciPy `_ to be installed or it will fail. See Also -------- astropy.coordinates.match_coordinates_sky SkyCoord.match_to_catalog_3d """ from .matching import match_coordinates_sky if (isinstance(catalogcoord, (SkyCoord, BaseCoordinateFrame)) and catalogcoord.has_data): self_in_catalog_frame = self.transform_to(catalogcoord) else: raise TypeError('Can only get separation to another SkyCoord or a ' 'coordinate frame with data') res = match_coordinates_sky(self_in_catalog_frame, catalogcoord, nthneighbor=nthneighbor, storekdtree='_kdtree_sky') return res def match_to_catalog_3d(self, catalogcoord, nthneighbor=1): """ Finds the nearest 3-dimensional matches of this coordinate to a set of catalog coordinates. This finds the 3-dimensional closest neighbor, which is only different from the on-sky distance if ``distance`` is set in this object or the ``catalogcoord`` object. For more on how to use this (and related) functionality, see the examples in :doc:`/coordinates/matchsep`. Parameters ---------- catalogcoord : `~astropy.coordinates.SkyCoord` or `~astropy.coordinates.BaseCoordinateFrame` The base catalog in which to search for matches. Typically this will be a coordinate object that is an array (i.e., ``catalogcoord.isscalar == False``) nthneighbor : int, optional Which closest neighbor to search for. Typically ``1`` is desired here, as that is correct for matching one set of coordinates to another. The next likely use case is ``2``, for matching a coordinate catalog against *itself* (``1`` is inappropriate because each point will find itself as the closest match). Returns ------- idx : integer array Indices into ``catalogcoord`` to get the matched points for each of this object's coordinates. Shape matches this object. sep2d : `~astropy.coordinates.Angle` The on-sky separation between the closest match for each element in this object in ``catalogcoord``. Shape matches this object. dist3d : `~astropy.units.Quantity` The 3D distance between the closest match for each element in this object in ``catalogcoord``. Shape matches this object. Notes ----- This method requires `SciPy `_ to be installed or it will fail. See Also -------- astropy.coordinates.match_coordinates_3d SkyCoord.match_to_catalog_sky """ from .matching import match_coordinates_3d if (isinstance(catalogcoord, (SkyCoord, BaseCoordinateFrame)) and catalogcoord.has_data): self_in_catalog_frame = self.transform_to(catalogcoord) else: raise TypeError('Can only get separation to another SkyCoord or a ' 'coordinate frame with data') res = match_coordinates_3d(self_in_catalog_frame, catalogcoord, nthneighbor=nthneighbor, storekdtree='_kdtree_3d') return res def search_around_sky(self, searcharoundcoords, seplimit): """ Searches for all coordinates in this object around a supplied set of points within a given on-sky separation. This is intended for use on `~astropy.coordinates.SkyCoord` objects with coordinate arrays, rather than a scalar coordinate. For a scalar coordinate, it is better to use `~astropy.coordinates.SkyCoord.separation`. For more on how to use this (and related) functionality, see the examples in :doc:`/coordinates/matchsep`. Parameters ---------- searcharoundcoords : `~astropy.coordinates.SkyCoord` or `~astropy.coordinates.BaseCoordinateFrame` The coordinates to search around to try to find matching points in this `SkyCoord`. This should be an object with array coordinates, not a scalar coordinate object. seplimit : `~astropy.units.Quantity` with angle units The on-sky separation to search within. Returns ------- idxsearcharound : integer array Indices into ``self`` that matches to the corresponding element of ``idxself``. Shape matches ``idxself``. idxself : integer array Indices into ``searcharoundcoords`` that matches to the corresponding element of ``idxsearcharound``. Shape matches ``idxsearcharound``. sep2d : `~astropy.coordinates.Angle` The on-sky separation between the coordinates. Shape matches ``idxsearcharound`` and ``idxself``. dist3d : `~astropy.units.Quantity` The 3D distance between the coordinates. Shape matches ``idxsearcharound`` and ``idxself``. Notes ----- This method requires `SciPy `_ (>=0.12.0) to be installed or it will fail. In the current implementation, the return values are always sorted in the same order as the ``searcharoundcoords`` (so ``idxsearcharound`` is in ascending order). This is considered an implementation detail, though, so it could change in a future release. See Also -------- astropy.coordinates.search_around_sky SkyCoord.search_around_3d """ from .matching import search_around_sky return search_around_sky(searcharoundcoords, self, seplimit, storekdtree='_kdtree_sky') def search_around_3d(self, searcharoundcoords, distlimit): """ Searches for all coordinates in this object around a supplied set of points within a given 3D radius. This is intended for use on `~astropy.coordinates.SkyCoord` objects with coordinate arrays, rather than a scalar coordinate. For a scalar coordinate, it is better to use `~astropy.coordinates.SkyCoord.separation_3d`. For more on how to use this (and related) functionality, see the examples in :doc:`/coordinates/matchsep`. Parameters ---------- searcharoundcoords : `~astropy.coordinates.SkyCoord` or `~astropy.coordinates.BaseCoordinateFrame` The coordinates to search around to try to find matching points in this `SkyCoord`. This should be an object with array coordinates, not a scalar coordinate object. distlimit : `~astropy.units.Quantity` with distance units The physical radius to search within. Returns ------- idxsearcharound : integer array Indices into ``self`` that matches to the corresponding element of ``idxself``. Shape matches ``idxself``. idxself : integer array Indices into ``searcharoundcoords`` that matches to the corresponding element of ``idxsearcharound``. Shape matches ``idxsearcharound``. sep2d : `~astropy.coordinates.Angle` The on-sky separation between the coordinates. Shape matches ``idxsearcharound`` and ``idxself``. dist3d : `~astropy.units.Quantity` The 3D distance between the coordinates. Shape matches ``idxsearcharound`` and ``idxself``. Notes ----- This method requires `SciPy `_ (>=0.12.0) to be installed or it will fail. In the current implementation, the return values are always sorted in the same order as the ``searcharoundcoords`` (so ``idxsearcharound`` is in ascending order). This is considered an implementation detail, though, so it could change in a future release. See Also -------- astropy.coordinates.search_around_3d SkyCoord.search_around_sky """ from .matching import search_around_3d return search_around_3d(searcharoundcoords, self, distlimit, storekdtree='_kdtree_3d') def position_angle(self, other): """ Computes the on-sky position angle (East of North) between this `SkyCoord` and another. Parameters ---------- other : `SkyCoord` The other coordinate to compute the position angle to. It is treated as the "head" of the vector of the position angle. Returns ------- pa : `~astropy.coordinates.Angle` The (positive) position angle of the vector pointing from ``self`` to ``other``. If either ``self`` or ``other`` contain arrays, this will be an array following the appropriate `numpy` broadcasting rules. Examples -------- >>> c1 = SkyCoord(0*u.deg, 0*u.deg) >>> c2 = SkyCoord(1*u.deg, 0*u.deg) >>> c1.position_angle(c2).degree 90.0 >>> c3 = SkyCoord(1*u.deg, 1*u.deg) >>> c1.position_angle(c3).degree # doctest: +FLOAT_CMP 44.995636455344844 """ from . import angle_utilities if self.frame.name == other.frame.name: other_in_self_frame = other else: other_in_self_frame = other.frame.transform_to(self.frame) slat = self.represent_as(UnitSphericalRepresentation).lat slon = self.represent_as(UnitSphericalRepresentation).lon olat = other_in_self_frame.represent_as(UnitSphericalRepresentation).lat olon = other_in_self_frame.represent_as(UnitSphericalRepresentation).lon return angle_utilities.position_angle(slon, slat, olon, olat) def skyoffset_frame(self, rotation=None): """ Returns the sky offset frame with this `SkyCoord` at the origin. Returns ------- astrframe : `~astropy.coordinates.SkyOffsetFrame` A sky offset frame of the same type as this `SkyCoord` (e.g., if this object has an ICRS coordinate, the resulting frame is SkyOffsetICRS, with the origin set to this object) rotation : `~astropy.coordinates.Angle` or `~astropy.units.Quantity` with angle units The final rotation of the frame about the ``origin``. The sign of the rotation is the left-hand rule. That is, an object at a particular position angle in the un-rotated system will be sent to the positive latitude (z) direction in the final frame. """ return SkyOffsetFrame(origin=self, rotation=rotation) def get_constellation(self, short_name=False, constellation_list='iau'): """ Determines the constellation(s) of the coordinates this `SkyCoord` contains. Parameters ---------- short_name : bool If True, the returned names are the IAU-sanctioned abbreviated names. Otherwise, full names for the constellations are used. constellation_list : str The set of constellations to use. Currently only ``'iau'`` is supported, meaning the 88 "modern" constellations endorsed by the IAU. Returns ------- constellation : str or string array If this is a scalar coordinate, returns the name of the constellation. If it is an array `SkyCoord`, it returns an array of names. Notes ----- To determine which constellation a point on the sky is in, this first precesses to B1875, and then uses the Delporte boundaries of the 88 modern constellations, as tabulated by `Roman 1987 `_. See Also -------- astropy.coordinates.get_constellation """ from .funcs import get_constellation return get_constellation(self, short_name, constellation_list) # WCS pixel to/from sky conversions def to_pixel(self, wcs, origin=0, mode='all'): """ Convert this coordinate to pixel coordinates using a `~astropy.wcs.WCS` object. Parameters ---------- wcs : `~astropy.wcs.WCS` The WCS to use for convert origin : int Whether to return 0 or 1-based pixel coordinates. mode : 'all' or 'wcs' Whether to do the transformation including distortions (``'all'``) or only including only the core WCS transformation (``'wcs'``). Returns ------- xp, yp : `numpy.ndarray` The pixel coordinates See Also -------- astropy.wcs.utils.skycoord_to_pixel : the implementation of this method """ return skycoord_to_pixel(self, wcs=wcs, origin=origin, mode=mode) @classmethod def from_pixel(cls, xp, yp, wcs, origin=0, mode='all'): """ Create a new `SkyCoord` from pixel coordinates using an `~astropy.wcs.WCS` object. Parameters ---------- xp, yp : float or `numpy.ndarray` The coordinates to convert. wcs : `~astropy.wcs.WCS` The WCS to use for convert origin : int Whether to return 0 or 1-based pixel coordinates. mode : 'all' or 'wcs' Whether to do the transformation including distortions (``'all'``) or only including only the core WCS transformation (``'wcs'``). Returns ------- coord : an instance of this class A new object with sky coordinates corresponding to the input ``xp`` and ``yp``. See Also -------- to_pixel : to do the inverse operation astropy.wcs.utils.pixel_to_skycoord : the implementation of this method """ return pixel_to_skycoord(xp, yp, wcs=wcs, origin=origin, mode=mode, cls=cls) # Table interactions @classmethod def guess_from_table(cls, table, **coord_kwargs): r""" A convenience method to create and return a new `SkyCoord` from the data in an astropy Table. This method matches table columns that start with the case-insensitive names of the the components of the requested frames, if they are also followed by a non-alphanumeric character. It will also match columns that *end* with the component name if a non-alphanumeric character is *before* it. For example, the first rule means columns with names like ``'RA[J2000]'`` or ``'ra'`` will be interpreted as ``ra`` attributes for `~astropy.coordinates.ICRS` frames, but ``'RAJ2000'`` or ``'radius'`` are *not*. Similarly, the second rule applied to the `~astropy.coordinates.Galactic` frame means that a column named ``'gal_l'`` will be used as the the ``l`` component, but ``gall`` or ``'fill'`` will not. The definition of alphanumeric here is based on Unicode's definition of alphanumeric, except without ``_`` (which is normally considered alphanumeric). So for ASCII, this means the non-alphanumeric characters are ``_!"#$%&'()*+,-./:;<=>?@[\]^`{|}~``). Parameters ---------- table : astropy.Table The table to load data from. coord_kwargs Any additional keyword arguments are passed directly to this class's constructor. Returns ------- newsc : same as this class The new `SkyCoord` (or subclass) object. """ inital_frame = coord_kwargs.get('frame') frame = _get_frame([], coord_kwargs) coord_kwargs['frame'] = inital_frame comp_kwargs = {} for comp_name in frame.representation_component_names: # this matches things like 'ra[...]'' but *not* 'rad'. # note that the "_" must be in there explicitly, because # "alphanumeric" usually includes underscores. starts_with_comp = comp_name + r'(\W|\b|_)' # this part matches stuff like 'center_ra', but *not* # 'aura' ends_with_comp = r'.*(\W|\b|_)' + comp_name + r'\b' #the final regex ORs together the two patterns rex = re.compile('(' +starts_with_comp + ')|(' + ends_with_comp + ')', re.IGNORECASE | re.UNICODE) for col_name in table.colnames: if rex.match(col_name): if comp_name in comp_kwargs: oldname = comp_kwargs[comp_name].name msg = ('Found at least two matches for component "{0}"' ': "{1}" and "{2}". Cannot continue with this ' 'ambiguity.') raise ValueError(msg.format(comp_name, oldname, col_name)) comp_kwargs[comp_name] = table[col_name] for k, v in comp_kwargs.items(): if k in coord_kwargs: raise ValueError('Found column "{0}" in table, but it was ' 'already provided as "{1}" keyword to ' 'guess_from_table function.'.format(v.name, k)) else: coord_kwargs[k] = v return cls(**coord_kwargs) # Name resolve @classmethod def from_name(cls, name, frame='icrs'): """ Given a name, query the CDS name resolver to attempt to retrieve coordinate information for that object. The search database, sesame url, and query timeout can be set through configuration items in ``astropy.coordinates.name_resolve`` -- see docstring for `~astropy.coordinates.get_icrs_coordinates` for more information. Parameters ---------- name : str The name of the object to get coordinates for, e.g. ``'M42'``. frame : str or `BaseCoordinateFrame` class or instance The frame to transform the object to. Returns ------- coord : SkyCoord Instance of the SkyCoord class. """ from .name_resolve import get_icrs_coordinates icrs_coord = get_icrs_coordinates(name) icrs_sky_coord = cls(icrs_coord) if frame in ('icrs', icrs_coord.__class__): return icrs_sky_coord else: return icrs_sky_coord.transform_to(frame) # <----------------Private utility functions below here-------------------------> def _get_frame_class(frame): """ Get a frame class from the input `frame`, which could be a frame name string, or frame class. """ import inspect if isinstance(frame, six.string_types): frame_names = frame_transform_graph.get_names() if frame not in frame_names: raise ValueError('Coordinate frame {0} not in allowed values {1}' .format(frame, sorted(frame_names))) frame_cls = frame_transform_graph.lookup_name(frame) elif inspect.isclass(frame) and issubclass(frame, BaseCoordinateFrame): frame_cls = frame else: raise ValueError('Coordinate frame must be a frame name or frame class') return frame_cls def _get_frame(args, kwargs): """ Determine the coordinate frame from input SkyCoord args and kwargs. This modifies args and/or kwargs in-place to remove the item that provided `frame`. It also infers the frame if an input coordinate was provided and checks for conflicts. This allows for frame to be specified as a string like 'icrs' or a frame class like ICRS, but not an instance ICRS() since the latter could have non-default representation attributes which would require a three-way merge. """ frame = kwargs.pop('frame', None) if frame is None and len(args) > 1: # We do not allow frames to be passed as positional arguments if data # is passed separately from frame. for arg in args: if isinstance(arg, (SkyCoord, BaseCoordinateFrame)): raise ValueError("{0} instance cannot be passed as a positional " "argument for the frame, pass it using the " "frame= keyword instead.".format(arg.__class__.__name__)) # If the frame is an instance or SkyCoord, we split up the attributes and # make it into a class. if isinstance(frame, SkyCoord): frame = frame.frame if isinstance(frame, BaseCoordinateFrame): for attr in frame.get_frame_attr_names(): if attr in kwargs: raise ValueError("cannot specify frame attribute '{0}' directly in SkyCoord since a frame instance was passed in".format(attr)) else: kwargs[attr] = getattr(frame, attr) frame = frame.__class__ if frame is not None: # Frame was provided as kwarg so validate and coerce into corresponding frame. frame_cls = _get_frame_class(frame) frame_specified_explicitly = True else: # Look for the frame in args for arg in args: try: frame_cls = _get_frame_class(arg) frame_specified_explicitly = True except ValueError: pass else: args.remove(arg) warnings.warn("Passing a frame as a positional argument is now " "deprecated, use the frame= keyword argument " "instead.", AstropyDeprecationWarning) break else: # Not in args nor kwargs - default to icrs frame_cls = ICRS frame_specified_explicitly = False # Check that the new frame doesn't conflict with existing coordinate frame # if a coordinate is supplied in the args list. If the frame still had not # been set by this point and a coordinate was supplied, then use that frame. for arg in args: coord_frame_cls = None if isinstance(arg, BaseCoordinateFrame): coord_frame_cls = arg.__class__ elif isinstance(arg, SkyCoord): coord_frame_cls = arg.frame.__class__ if coord_frame_cls is not None: if not frame_specified_explicitly: frame_cls = coord_frame_cls elif frame_cls is not coord_frame_cls: raise ValueError("Cannot override frame='{0}' of input coordinate with " "new frame='{1}'. Instead transform the coordinate." .format(coord_frame_cls.__name__, frame_cls.__name__)) if 'representation' in kwargs: frame = frame_cls(representation=_get_repr_cls(kwargs['representation'])) else: frame = frame_cls() return frame def _get_units(args, kwargs): """ Get the longitude unit and latitude unit from kwargs. Possible enhancement is to allow input from args as well. """ if 'unit' not in kwargs: units = [None, None, None] else: units = kwargs.pop('unit') if isinstance(units, six.string_types): units = [x.strip() for x in units.split(',')] # Allow for input like unit='deg' or unit='m' if len(units) == 1: units = [units[0], units[0], units[0]] elif isinstance(units, (Unit, IrreducibleUnit)): units = [units, units, units] try: units = [(Unit(x) if x else None) for x in units] units.extend(None for x in range(3 - len(units))) if len(units) > 3: raise ValueError() except Exception: raise ValueError('Unit keyword must have one to three unit values as ' 'tuple or comma-separated string') return units def _parse_coordinate_arg(coords, frame, units, init_kwargs): """ Single unnamed arg supplied. This must be: - Coordinate frame with data - Representation - SkyCoord - List or tuple of: - String which splits into two values - Iterable with two values - SkyCoord, frame, or representation objects. Returns a dict mapping coordinate attribute names to values (or lists of values) """ is_scalar = False # Differentiate between scalar and list input valid_kwargs = {} # Returned dict of lon, lat, and distance (optional) frame_attr_names = frame.representation_component_names.keys() repr_attr_names = frame.representation_component_names.values() repr_attr_classes = frame.representation.attr_classes.values() n_attr_names = len(repr_attr_names) # Turn a single string into a list of strings for convenience if isinstance(coords, six.string_types): is_scalar = True coords = [coords] if isinstance(coords, (SkyCoord, BaseCoordinateFrame)): # Note that during parsing of `frame` it is checked that any coordinate # args have the same frame as explicitly supplied, so don't worry here. if not coords.has_data: raise ValueError('Cannot initialize from a frame without coordinate data') data = coords.data.represent_as(frame.representation) values = [] # List of values corresponding to representation attrs for repr_attr_name in repr_attr_names: # If coords did not have an explicit distance then don't include in initializers. if (isinstance(coords.data, UnitSphericalRepresentation) and repr_attr_name == 'distance'): continue # Get the value from `data` in the eventual representation values.append(getattr(data, repr_attr_name)) for attr in FRAME_ATTR_NAMES_SET(): value = getattr(coords, attr, None) use_value = (isinstance(coords, SkyCoord) or attr not in coords._attr_names_with_defaults) if use_value and value is not None: valid_kwargs[attr] = value elif isinstance(coords, BaseRepresentation): data = coords.represent_as(frame.representation) values = [getattr(data, repr_attr_name) for repr_attr_name in repr_attr_names] elif (isinstance(coords, np.ndarray) and coords.dtype.kind in 'if' and coords.ndim == 2 and coords.shape[1] <= 3): # 2-d array of coordinate values. Handle specially for efficiency. values = coords.transpose() # Iterates over repr attrs elif isinstance(coords, (collections.Sequence, np.ndarray)): # Handles list-like input. vals = [] is_ra_dec_representation = ('ra' in frame.representation_component_names and 'dec' in frame.representation_component_names) coord_types = (SkyCoord, BaseCoordinateFrame, BaseRepresentation) if any(isinstance(coord, coord_types) for coord in coords): # this parsing path is used when there are coordinate-like objects # in the list - instead of creating lists of values, we create # SkyCoords from the list elements and then combine them. scs = [SkyCoord(coord, **init_kwargs) for coord in coords] # Check that all frames are equivalent for sc in scs[1:]: if not sc.is_equivalent_frame(scs[0]): raise ValueError("List of inputs don't have equivalent " "frames: {0} != {1}".format(sc, scs[0])) # Now use the first to determine if they are all UnitSpherical allunitsphrepr = isinstance(scs[0].data, UnitSphericalRepresentation) # get the frame attributes from the first one, because from above we # know it matches all the others for fattrnm in FRAME_ATTR_NAMES_SET(): valid_kwargs[fattrnm] = getattr(scs[0], fattrnm) # Now combine the values, to be used below values = [] for data_attr_name, repr_attr_name in zip(frame_attr_names, repr_attr_names): if allunitsphrepr and repr_attr_name == 'distance': #if they are *all* UnitSpherical, don't give a distance continue data_vals = [] for sc in scs: data_val = getattr(sc, data_attr_name) data_vals.append(data_val.reshape(1,) if sc.isscalar else data_val) concat_vals = np.concatenate(data_vals) # Hack because np.concatenate doesn't fully work with Quantity if isinstance(concat_vals, u.Quantity): concat_vals._unit = data_val.unit values.append(concat_vals) else: #none of the elements are "frame-like" #turn into a list of lists like [[v1_0, v2_0, v3_0], ... [v1_N, v2_N, v3_N]] for coord in coords: if isinstance(coord, six.string_types): coord1 = coord.split() if len(coord1) == 6: coord = (' '.join(coord1[:3]), ' '.join(coord1[3:])) elif is_ra_dec_representation: coord = _parse_ra_dec(coord) else: coord = coord1 vals.append(coord) # Assumes coord is a sequence at this point # Do some basic validation of the list elements: all have a length and all # lengths the same try: n_coords = sorted(set(len(x) for x in vals)) except Exception: raise ValueError('One or more elements of input sequence does not have a length') if len(n_coords) > 1: raise ValueError('Input coordinate values must have same number of elements, found {0}' .format(n_coords)) n_coords = n_coords[0] # Must have no more coord inputs than representation attributes if n_coords > n_attr_names: raise ValueError('Input coordinates have {0} values but ' 'representation {1} only accepts {2}' .format(n_coords, frame.representation.get_name(), n_attr_names)) # Now transpose vals to get [(v1_0 .. v1_N), (v2_0 .. v2_N), (v3_0 .. v3_N)] # (ok since we know it is exactly rectangular). (Note: can't just use zip(*values) # because Longitude et al distinguishes list from tuple so [a1, a2, ..] is needed # while (a1, a2, ..) doesn't work. values = [list(x) for x in zip(*vals)] if is_scalar: values = [x[0] for x in values] else: raise ValueError('Cannot parse coordinates from first argument') # Finally we have a list of values from which to create the keyword args # for the frame initialization. Validate by running through the appropriate # class initializer and supply units (which might be None). try: for frame_attr_name, repr_attr_class, value, unit in zip( frame_attr_names, repr_attr_classes, values, units): valid_kwargs[frame_attr_name] = repr_attr_class(value, unit=unit, copy=False) except Exception as err: raise ValueError('Cannot parse first argument data "{0}" for attribute ' '{1}'.format(value, frame_attr_name), err) return valid_kwargs def _get_representation_attrs(frame, units, kwargs): """ Find instances of the "representation attributes" for specifying data for this frame. Pop them off of kwargs, run through the appropriate class constructor (to validate and apply unit), and put into the output valid_kwargs. "Representation attributes" are the frame-specific aliases for the underlying data values in the representation, e.g. "ra" for "lon" for many equatorial spherical representations, or "w" for "x" in the cartesian representation of Galactic. """ frame_attr_names = frame.representation_component_names.keys() repr_attr_classes = frame.representation.attr_classes.values() valid_kwargs = {} for frame_attr_name, repr_attr_class, unit in zip(frame_attr_names, repr_attr_classes, units): value = kwargs.pop(frame_attr_name, None) if value is not None: valid_kwargs[frame_attr_name] = repr_attr_class(value, unit=unit) return valid_kwargs def _parse_ra_dec(coord_str): """ Parse RA and Dec values from a coordinate string. Currently the following formats are supported: * space separated 6-value format * space separated <6-value format, this requires a plus or minus sign separation between RA and Dec * sign separated format * JHHMMSS.ss+DDMMSS.ss format, with up to two optional decimal digits * JDDDMMSS.ss+DDMMSS.ss format, with up to two optional decimal digits Parameters ---------- coord_str : str Coordinate string to parse. Returns ------- coord : str or list of str Parsed coordinate values. """ if isinstance(coord_str, six.string_types): coord1 = coord_str.split() else: # This exception should never be raised from SkyCoord raise TypeError('coord_str must be a single str') if len(coord1) == 6: coord = (' '.join(coord1[:3]), ' '.join(coord1[3:])) elif len(coord1) > 2: coord = PLUS_MINUS_RE.split(coord_str) coord = (coord[0], ' '.join(coord[1:])) elif len(coord1) == 1: match_j = J_PREFIXED_RA_DEC_RE.match(coord_str) if match_j: coord = match_j.groups() if len(coord[0].split('.')[0]) == 7: coord = ('{0} {1} {2}'. format(coord[0][0:3], coord[0][3:5], coord[0][5:]), '{0} {1} {2}'. format(coord[1][0:3], coord[1][3:5], coord[1][5:])) else: coord = ('{0} {1} {2}'. format(coord[0][0:2], coord[0][2:4], coord[0][4:]), '{0} {1} {2}'. format(coord[1][0:3], coord[1][3:5], coord[1][5:])) else: coord = PLUS_MINUS_RE.split(coord_str) coord = (coord[0], ' '.join(coord[1:])) else: coord = coord1 return coord