# -*- coding: utf-8 -*-
# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
Framework and base classes for coordinate frames/"low-level" coordinate
classes.
"""
from __future__ import (absolute_import, unicode_literals, division,
print_function)
# Standard library
import inspect
from copy import deepcopy
from collections import namedtuple, OrderedDict
# Dependencies
import numpy as np
# Project
from ..utils.compat.misc import override__dir__
from ..extern import six
from .. import units as u
from ..utils import OrderedDescriptor, OrderedDescriptorContainer
from .transformations import TransformGraph
from .representation import (BaseRepresentation, CartesianRepresentation,
SphericalRepresentation,
UnitSphericalRepresentation,
REPRESENTATION_CLASSES)
__all__ = ['BaseCoordinateFrame', 'frame_transform_graph', 'GenericFrame',
'FrameAttribute', 'TimeFrameAttribute', 'QuantityFrameAttribute',
'EarthLocationAttribute', 'RepresentationMapping',
'CoordinateAttribute']
# the graph used for all transformations between frames
frame_transform_graph = TransformGraph()
def _get_repr_cls(value):
"""
Return a valid representation class from ``value`` or raise exception.
"""
if value in REPRESENTATION_CLASSES:
value = REPRESENTATION_CLASSES[value]
try:
# value might not be a class, so use try
assert issubclass(value, BaseRepresentation)
except (TypeError, AssertionError):
raise ValueError(
'Representation is {0!r} but must be a BaseRepresentation class '
'or one of the string aliases {1}'.format(
value, list(REPRESENTATION_CLASSES)))
return value
class FrameMeta(OrderedDescriptorContainer):
def __new__(mcls, name, bases, members):
if 'default_representation' in members:
default_repr = members.pop('default_representation')
found_default_repr = True
else:
default_repr = None
found_default_repr = False
if 'frame_specific_representation_info' in members:
repr_info = members.pop('frame_specific_representation_info')
found_repr_info = True
else:
repr_info = None
found_repr_info = False
# somewhat hacky, but this is the best way to get the MRO according to
# https://mail.python.org/pipermail/python-list/2002-December/167861.html
tmp_cls = super(FrameMeta, mcls).__new__(mcls, name, bases, members)
# now look through the whole MRO for the class attributes, raw for
# frame_attr_names, and leading underscore for others
for m in (c.__dict__ for c in tmp_cls.__mro__):
if not found_default_repr and '_default_representation' in m:
default_repr = m['_default_representation']
found_default_repr = True
if (not found_repr_info and
'_frame_specific_representation_info' in m):
repr_info = m['_frame_specific_representation_info']
found_repr_info = True
if found_default_repr and found_repr_info:
break
else:
raise ValueError(
'Could not find all expected BaseCoordinateFrame class '
'attributes. Are you mis-using FrameMeta?')
# Make read-only properties for the frame class attributes that should
# be read-only to make them immutable after creation.
# We copy attributes instead of linking to make sure there's no
# accidental cross-talk between classes
mcls.readonly_prop_factory(members, 'default_representation',
default_repr)
mcls.readonly_prop_factory(members,
'frame_specific_representation_info',
deepcopy(repr_info))
# now set the frame name as lower-case class name, if it isn't explicit
if 'name' not in members:
members['name'] = name.lower()
return super(FrameMeta, mcls).__new__(mcls, name, bases, members)
@staticmethod
def readonly_prop_factory(members, attr, value):
private_attr = '_' + attr
def getter(self):
return getattr(self, private_attr)
members[private_attr] = value
members[attr] = property(getter)
class FrameAttribute(OrderedDescriptor):
"""A non-mutable data descriptor to hold a frame attribute.
This class must be used to define frame attributes (e.g. ``equinox`` or
``obstime``) that are included in a frame class definition.
Examples
--------
The `~astropy.coordinates.FK4` class uses the following class attributes::
class FK4(BaseCoordinateFrame):
equinox = TimeFrameAttribute(default=_EQUINOX_B1950)
obstime = TimeFrameAttribute(default=None,
secondary_attribute='equinox')
This means that ``equinox`` and ``obstime`` are available to be set as
keyword arguments when creating an ``FK4`` class instance and are then
accessible as instance attributes. The instance value for the attribute
must be stored in ``'_' + <attribute_name>`` by the frame ``__init__``
method.
Note in this example that ``equinox`` and ``obstime`` are time attributes
and use the ``TimeAttributeFrame`` class. This subclass overrides the
``convert_input`` method to validate and convert inputs into a ``Time``
object.
Parameters
----------
default : object
Default value for the attribute if not provided
secondary_attribute : str
Name of a secondary instance attribute which supplies the value if
``default is None`` and no value was supplied during initialization.
"""
_class_attribute_ = 'frame_attributes'
_name_attribute_ = 'name'
name = '<unbound>'
def __init__(self, default=None, secondary_attribute=''):
self.default = default
self.secondary_attribute = secondary_attribute
super(FrameAttribute, self).__init__()
def convert_input(self, value):
"""
Validate the input ``value`` and convert to expected attribute class.
The base method here does nothing, but subclasses can implement this
as needed. The method should catch any internal exceptions and raise
ValueError with an informative message.
The method returns the validated input along with a boolean that
indicates whether the input value was actually converted. If the input
value was already the correct type then the ``converted`` return value
should be ``False``.
Parameters
----------
value : object
Input value to be converted.
Returns
-------
output_value
The ``value`` converted to the correct type (or just ``value`` if
``converted`` is False)
converted : bool
True if the conversion was actually performed, False otherwise.
Raises
------
ValueError
If the input is not valid for this attribute.
"""
return value, False
def __get__(self, instance, frame_cls=None):
out = None
if instance is not None:
out = getattr(instance, '_' + self.name, None)
if out is None and self.default is None:
out = getattr(instance, self.secondary_attribute, None)
if out is None:
out = self.default
out, converted = self.convert_input(out)
if instance is not None and converted:
setattr(instance, '_' + self.name, out)
return out
def __set__(self, instance, val):
raise AttributeError('Cannot set frame attribute')
class TimeFrameAttribute(FrameAttribute):
"""
Frame attribute descriptor for quantities that are Time objects.
See the `~astropy.coordinates.FrameAttribute` API doc for further
information.
Parameters
----------
default : object
Default value for the attribute if not provided
secondary_attribute : str
Name of a secondary instance attribute which supplies the value if
``default is None`` and no value was supplied during initialization.
"""
def convert_input(self, value):
"""
Convert input value to a Time object and validate by running through
the Time constructor. Also check that the input was a scalar.
Parameters
----------
value : object
Input value to be converted.
Returns
-------
out, converted : correctly-typed object, boolean
Tuple consisting of the correctly-typed object and a boolean which
indicates if conversion was actually performed.
Raises
------
ValueError
If the input is not valid for this attribute.
"""
from ..time import Time
if value is None:
return None, False
if isinstance(value, Time):
out = value
converted = False
else:
try:
out = Time(value)
except Exception as err:
raise ValueError(
'Invalid time input {0}={1!r}\n{2}'.format(self.name,
value, err))
converted = True
return out, converted
class QuantityFrameAttribute(FrameAttribute):
"""
A frame attribute that is a quantity with specified units and shape
(optionally).
Parameters
----------
default : object
Default value for the attribute if not provided
secondary_attribute : str
Name of a secondary instance attribute which supplies the value if
``default is None`` and no value was supplied during initialization.
unit : unit object or None
Name of a unit that the input will be converted into. If None, no
unit-checking or conversion is performed
shape : tuple or None
If given, specifies the shape the attribute must be
"""
def __init__(self, default=None, secondary_attribute='', unit=None, shape=None):
super(QuantityFrameAttribute, self).__init__(default, secondary_attribute)
self.unit = unit
self.shape = shape
def convert_input(self, value):
"""
Checks that the input is a Quantity with the necessary units (or the
special value ``0``).
Parameters
----------
value : object
Input value to be converted.
Returns
-------
out, converted : correctly-typed object, boolean
Tuple consisting of the correctly-typed object and a boolean which
indicates if conversion was actually performed.
Raises
------
ValueError
If the input is not valid for this attribute.
"""
if np.all(value == 0) and self.unit is not None and self.unit is not None:
return u.Quantity(np.zeros(self.shape), self.unit), True
else:
converted = True
if not (hasattr(value, 'unit') ):
raise TypeError('Tried to set a QuantityFrameAttribute with '
'something that does not have a unit.')
oldvalue = value
value = u.Quantity(oldvalue, copy=False).to(self.unit)
if self.shape is not None and value.shape != self.shape:
raise ValueError('The provided value has shape "{0}", but '
'should have shape "{1}"'.format(value.shape,
self.shape))
if (oldvalue.unit == value.unit and hasattr(oldvalue, 'value') and
np.all(oldvalue.value == value.value)):
converted = False
return value, converted
class EarthLocationAttribute(FrameAttribute):
"""
A frame attribute that can act as a `~astropy.coordinates.EarthLocation`.
It can be created as anything that can be transformed to the
`~astropy.coordinates.ITRS` frame, but always presents as an `EarthLocation`
when accessed after creation.
Parameters
----------
default : object
Default value for the attribute if not provided
secondary_attribute : str
Name of a secondary instance attribute which supplies the value if
``default is None`` and no value was supplied during initialization.
"""
def convert_input(self, value):
"""
Checks that the input is a Quantity with the necessary units (or the
special value ``0``).
Parameters
----------
value : object
Input value to be converted.
Returns
-------
out, converted : correctly-typed object, boolean
Tuple consisting of the correctly-typed object and a boolean which
indicates if conversion was actually performed.
Raises
------
ValueError
If the input is not valid for this attribute.
"""
if value is None:
return None, False
elif isinstance(value, EarthLocation):
return value, False
else:
#we have to do the import here because of some tricky circular deps
from .builtin_frames import ITRS
if not hasattr(value, 'transform_to'):
raise ValueError('"{0}" was passed into an '
'EarthLocationAttribute, but it does not have '
'"transform_to" method'.format(value))
itrsobj = value.transform_to(ITRS)
return itrsobj.earth_location, True
class CoordinateAttribute(FrameAttribute):
"""
A frame attribute which is a coordinate object. It can be given as a
low-level frame class *or* a `~astropy.coordinates.SkyCoord`, but will
always be converted to the low-level frame class when accessed.
Parameters
----------
frame : a coordinate frame class
The type of frame this attribute can be
default : object
Default value for the attribute if not provided
secondary_attribute : str
Name of a secondary instance attribute which supplies the value if
``default is None`` and no value was supplied during initialization.
"""
def __init__(self, frame, default=None, secondary_attribute=''):
self._frame = frame
super(CoordinateAttribute, self).__init__(default, secondary_attribute)
def convert_input(self, value):
"""
Checks that the input is a SkyCoord with the necessary units (or the
special value ``None``).
Parameters
----------
value : object
Input value to be converted.
Returns
-------
out, converted : correctly-typed object, boolean
Tuple consisting of the correctly-typed object and a boolean which
indicates if conversion was actually performed.
Raises
------
ValueError
If the input is not valid for this attribute.
"""
if value is None:
return None, False
elif isinstance(value, self._frame):
return value, False
else:
if not hasattr(value, 'transform_to'):
raise ValueError('"{0}" was passed into a '
'CoordinateAttribute, but it does not have '
'"transform_to" method'.format(value))
transformedobj = value.transform_to(self._frame)
if hasattr(transformedobj, 'frame'):
transformedobj = transformedobj.frame
return transformedobj, True
_RepresentationMappingBase = \
namedtuple('RepresentationMapping',
('reprname', 'framename', 'defaultunit'))
class RepresentationMapping(_RepresentationMappingBase):
"""
This `~collections.namedtuple` is used with the
``frame_specific_representation_info`` attribute to tell frames what
attribute names (and default units) to use for a particular representation.
``reprname`` and ``framename`` should be strings, while ``defaultunit`` can
be either an astropy unit, the string ``'recommended'`` (to use whatever
the representation's ``recommended_units`` is), or None (to indicate that
no unit mapping should be done).
"""
def __new__(cls, reprname, framename, defaultunit='recommended'):
# this trick just provides some defaults
return super(RepresentationMapping, cls).__new__(cls, reprname,
framename,
defaultunit)
@six.add_metaclass(FrameMeta)
class BaseCoordinateFrame(object):
"""
The base class for coordinate frames.
This class is intended to be subclassed to create instances of specific
systems. Subclasses can implement the following attributes:
* `default_representation`
A subclass of `~astropy.coordinates.BaseRepresentation` that will be
treated as the default representation of this frame. This is the
representation assumed by default when the frame is created.
* `~astropy.coordinates.FrameAttribute` class attributes
Frame attributes such as ``FK4.equinox`` or ``FK4.obstime`` are defined
using a descriptor class. See the narrative documentation or
built-in classes code for details.
* `frame_specific_representation_info`
A dictionary mapping the name or class of a representation to a list of
`~astropy.coordinates.RepresentationMapping` objects that tell what
names and default units should be used on this frame for the components
of that representation.
Parameters
----------
representation : `BaseRepresentation` or None
A representation object or `None` to have no data (or use the other
arguments)
*args, **kwargs
Coordinates, with names that depend on the subclass.
copy : bool, optional
If `True` (default), make copies of the input coordinate arrays.
Can only be passed in as a keyword argument.
"""
default_representation = None
# specifies special names/units for representation attributes
frame_specific_representation_info = {}
_inherit_descriptors_ = (FrameAttribute,)
frame_attributes = OrderedDict()
# Default empty frame_attributes dict
def __init__(self, *args, **kwargs):
copy = kwargs.pop('copy', True)
self._attr_names_with_defaults = []
if 'representation' in kwargs:
self.representation = kwargs.pop('representation')
# if not set below, this is a frame with no data
representation_data = None
for fnm, fdefault in self.get_frame_attr_names().items():
# Read-only frame attributes are defined as FrameAttribue
# descriptors which are not settable, so set 'real' attributes as
# the name prefaced with an underscore.
if fnm in kwargs:
value = kwargs.pop(fnm)
setattr(self, '_' + fnm, value)
else:
setattr(self, '_' + fnm, fdefault)
self._attr_names_with_defaults.append(fnm)
# Validate input by getting the attribute here.
getattr(self, fnm)
args = list(args) # need to be able to pop them
if (len(args) > 0) and (isinstance(args[0], BaseRepresentation) or
args[0] is None):
representation_data = args.pop(0)
if len(args) > 0:
raise TypeError(
'Cannot create a frame with both a representation and '
'other positional arguments')
elif self.representation:
repr_kwargs = {}
for nmkw, nmrep in self.representation_component_names.items():
if len(args) > 0:
#first gather up positional args
repr_kwargs[nmrep] = args.pop(0)
elif nmkw in kwargs:
repr_kwargs[nmrep] = kwargs.pop(nmkw)
#special-case the Spherical->UnitSpherical if no `distance`
#TODO: possibly generalize this somehow?
if repr_kwargs:
if repr_kwargs.get('distance', True) is None:
del repr_kwargs['distance']
if (issubclass(self.representation, SphericalRepresentation) and
'distance' not in repr_kwargs):
representation = self.representation._unit_representation
else:
representation = self.representation
representation_data = representation(copy=copy, **repr_kwargs)
if len(args) > 0:
raise TypeError(
'{0}.__init__ had {1} remaining unhandled arguments'.format(
self.__class__.__name__, len(args)))
if kwargs:
raise TypeError(
'Coordinate frame got unexpected keywords: {0}'.format(
list(kwargs)))
self._data = representation_data
# We do ``is not None`` because self._data might evaluate to false for
# empty arrays or data == 0
if self._data is not None:
self._rep_cache = dict()
self._rep_cache[self._data.__class__.__name__, False] = self._data
@property
def data(self):
"""
The coordinate data for this object. If this frame has no data, an
`ValueError` will be raised. Use `has_data` to
check if data is present on this frame object.
"""
if self._data is None:
raise ValueError('The frame object "{0}" does not have associated '
'data'.format(repr(self)))
return self._data
@property
def has_data(self):
"""
True if this frame has `data`, False otherwise.
"""
return self._data is not None
def __len__(self):
return len(self.data)
def __nonzero__(self): # Py 2.x
return self.isscalar or len(self) != 0
def __bool__(self): # Py 3.x
return self.isscalar or len(self) != 0
@property
def shape(self):
return self.data.shape
@property
def isscalar(self):
return self.data.isscalar
@classmethod
def get_frame_attr_names(cls):
return OrderedDict((name, getattr(cls, name))
for name in cls.frame_attributes)
@property
def representation(self):
"""
The representation of the data in this frame, as a class that is
subclassed from `~astropy.coordinates.BaseRepresentation`. Can
also be *set* using the string name of the representation.
"""
if not hasattr(self, '_representation'):
self._representation = self.default_representation
return self._representation
@representation.setter
def representation(self, value):
self._representation = _get_repr_cls(value)
@classmethod
def _get_representation_info(cls):
# This exists as a class method only to support handling frame inputs
# without units, which are deprecated and will be removed. This can be
# moved into the representation_info property at that time.
repr_attrs = {}
for repr_cls in REPRESENTATION_CLASSES.values():
repr_attrs[repr_cls] = {'names': [], 'units': []}
for c in repr_cls.attr_classes.keys():
repr_attrs[repr_cls]['names'].append(c)
rec_unit = repr_cls.recommended_units.get(c, None)
repr_attrs[repr_cls]['units'].append(rec_unit)
for repr_cls, mappings in cls._frame_specific_representation_info.items():
# keys may be a class object or a name
repr_cls = _get_repr_cls(repr_cls)
# take the 'names' and 'units' tuples from repr_attrs,
# and then use the RepresentationMapping objects
# to update as needed for this frame.
nms = repr_attrs[repr_cls]['names']
uns = repr_attrs[repr_cls]['units']
comptomap = dict([(m.reprname, m) for m in mappings])
for i, c in enumerate(repr_cls.attr_classes.keys()):
if c in comptomap:
mapp = comptomap[c]
nms[i] = mapp.framename
# need the isinstance because otherwise if it's a unit it
# will try to compare to the unit string representation
if not (isinstance(mapp.defaultunit, six.string_types) and
mapp.defaultunit == 'recommended'):
uns[i] = mapp.defaultunit
# else we just leave it as recommended_units says above
# Convert to tuples so that this can't mess with frame internals
repr_attrs[repr_cls]['names'] = tuple(nms)
repr_attrs[repr_cls]['units'] = tuple(uns)
return repr_attrs
@property
def representation_info(self):
"""
A dictionary with the information of what attribute names for this frame
apply to particular representations.
"""
return self._get_representation_info()
@property
def representation_component_names(self):
out = OrderedDict()
if self.representation is None:
return out
data_names = self.representation.attr_classes.keys()
repr_names = self.representation_info[self.representation]['names']
for repr_name, data_name in zip(repr_names, data_names):
out[repr_name] = data_name
return out
@property
def representation_component_units(self):
out = OrderedDict()
if self.representation is None:
return out
repr_attrs = self.representation_info[self.representation]
repr_names = repr_attrs['names']
repr_units = repr_attrs['units']
for repr_name, repr_unit in zip(repr_names, repr_units):
if repr_unit:
out[repr_name] = repr_unit
return out
def realize_frame(self, representation):
"""
Generates a new frame *with new data* from another frame (which may or
may not have data).
Parameters
----------
representation : BaseRepresentation
The representation to use as the data for the new frame.
Returns
-------
frameobj : same as this frame
A new object with the same frame attributes as this one, but
with the ``representation`` as the data.
"""
frattrs = dict([(attr, getattr(self, attr))
for attr in self.get_frame_attr_names()
if attr not in self._attr_names_with_defaults])
return self.__class__(representation, **frattrs)
def represent_as(self, new_representation, in_frame_units=False):
"""
Generate and return a new representation of this frame's `data`
as a Representation object.
Note: In order to make an in-place change of the representation
of a Frame or SkyCoord object, set the ``representation``
attribute of that object to the desired new representation.
Parameters
----------
new_representation : subclass of BaseRepresentation or string
The type of representation to generate. May be a *class*
(not an instance), or the string name of the representation
class.
in_frame_units : bool
Force the representation units to match the specified units
particular to this frame
Returns
-------
newrep : BaseRepresentation-derived object
A new representation object of this frame's `data`.
Raises
------
AttributeError
If this object had no `data`
Examples
--------
>>> from astropy import units as u
>>> from astropy.coordinates import SkyCoord, CartesianRepresentation
>>> coord = SkyCoord(0*u.deg, 0*u.deg)
>>> coord.represent_as(CartesianRepresentation)
<CartesianRepresentation (x, y, z) [dimensionless]
(1.0, 0.0, 0.0)>
>>> coord.representation = CartesianRepresentation
>>> coord
<SkyCoord (ICRS): (x, y, z) [dimensionless]
(1.0, 0.0, 0.0)>
"""
new_representation = _get_repr_cls(new_representation)
cached_repr = self._rep_cache.get((new_representation.__name__,
in_frame_units))
if not cached_repr:
data = self.data.represent_as(new_representation)
# If the new representation is known to this frame and has a defined
# set of names and units, then use that.
new_attrs = self.representation_info.get(new_representation)
if new_attrs and in_frame_units:
datakwargs = dict((comp, getattr(data, comp))
for comp in data.components)
for comp, new_attr_unit in zip(data.components, new_attrs['units']):
if new_attr_unit:
datakwargs[comp] = datakwargs[comp].to(new_attr_unit)
data = data.__class__(copy=False, **datakwargs)
self._rep_cache[new_representation.__name__, in_frame_units] = data
return self._rep_cache[new_representation.__name__, in_frame_units]
def transform_to(self, new_frame):
"""
Transform this object's coordinate data to a new frame.
Parameters
----------
new_frame : class or frame object or SkyCoord object
The frame to transform this coordinate frame into.
Returns
-------
transframe
A new object with the coordinate data represented in the
``newframe`` system.
Raises
------
ValueError
If there is no possible transformation route.
"""
from .errors import ConvertError
if self._data is None:
raise ValueError('Cannot transform a frame with no data')
if inspect.isclass(new_frame):
#means use the defaults for this class
new_frame = new_frame()
if hasattr(new_frame, '_sky_coord_frame'):
# Input new_frame is not a frame instance or class and is most
# likely a SkyCoord object.
new_frame = new_frame._sky_coord_frame
trans = frame_transform_graph.get_transform(self.__class__,
new_frame.__class__)
if trans is None:
if new_frame is self.__class__:
# no special transform needed, but should update frame info
return new_frame.realize_frame(self.data)
msg = 'Cannot transform from {0} to {1}'
raise ConvertError(msg.format(self.__class__, new_frame.__class__))
return trans(self, new_frame)
def is_transformable_to(self, new_frame):
"""
Determines if this coordinate frame can be transformed to another
given frame.
Parameters
----------
new_frame : class or frame object
The proposed frame to transform into.
Returns
-------
transformable : bool or str
`True` if this can be transformed to ``new_frame``, `False` if
not, or the string 'same' if ``new_frame`` is the same system as
this object but no transformation is defined.
Notes
-----
A return value of 'same' means the transformation will work, but it will
just give back a copy of this object. The intended usage is::
if coord.is_transformable_to(some_unknown_frame):
coord2 = coord.transform_to(some_unknown_frame)
This will work even if ``some_unknown_frame`` turns out to be the same
frame class as ``coord``. This is intended for cases where the frame
is the same regardless of the frame attributes (e.g. ICRS), but be
aware that it *might* also indicate that someone forgot to define the
transformation between two objects of the same frame class but with
different attributes.
"""
new_frame_cls = new_frame if inspect.isclass(new_frame) else new_frame.__class__
trans = frame_transform_graph.get_transform(self.__class__, new_frame_cls)
if trans is None:
if new_frame_cls is self.__class__:
return 'same'
else:
return False
else:
return True
def is_frame_attr_default(self, attrnm):
"""
Determine whether or not a frame attribute has its value because it's
the default value, or because this frame was created with that value
explicitly requested.
Parameters
----------
attrnm : str
The name of the attribute to check.
Returns
-------
isdefault : bool
True if the attribute ``attrnm`` has its value by default, False if
it was specified at creation of this frame.
"""
return attrnm in self._attr_names_with_defaults
def is_equivalent_frame(self, other):
"""
Checks if this object is the same frame as the ``other`` object.
To be the same frame, two objects must be the same frame class and have
the same frame attributes. Note that it does *not* matter what, if any,
data either object has.
Parameters
----------
other : BaseCoordinateFrame
the other frame to check
Returns
-------
isequiv : bool
True if the frames are the same, False if not.
Raises
------
TypeError
If ``other`` isn't a `BaseCoordinateFrame` or subclass.
"""
if self.__class__ == other.__class__:
for frame_attr_name in self.get_frame_attr_names():
if getattr(self, frame_attr_name) != getattr(other, frame_attr_name):
return False
return True
elif not isinstance(other, BaseCoordinateFrame):
raise TypeError("Tried to do is_equivalent_frame on something that "
"isn't a frame")
else:
return False
def __repr__(self):
frameattrs = self._frame_attrs_repr()
data_repr = self._data_repr()
if frameattrs:
frameattrs = ' ({0})'.format(frameattrs)
if data_repr:
return '<{0} Coordinate{1}: {2}>'.format(self.__class__.__name__,
frameattrs, data_repr)
else:
return '<{0} Frame{1}>'.format(self.__class__.__name__,
frameattrs)
def _data_repr(self):
"""Returns a string representation of the coordinate data."""
if not self.has_data:
return ''
if self.representation:
if (issubclass(self.representation, SphericalRepresentation) and
isinstance(self.data, UnitSphericalRepresentation)):
data = self.represent_as(self.data.__class__,
in_frame_units=True)
else:
data = self.represent_as(self.representation,
in_frame_units=True)
data_repr = repr(data)
for nmpref, nmrepr in self.representation_component_names.items():
data_repr = data_repr.replace(nmrepr, nmpref)
else:
data = self.data
data_repr = repr(self.data)
if data_repr.startswith('<' + data.__class__.__name__):
# remove both the leading "<" and the space after the name, as well
# as the trailing ">"
data_repr = data_repr[(len(data.__class__.__name__) + 2):-1]
else:
data_repr = 'Data:\n' + data_repr
return data_repr
def _frame_attrs_repr(self):
"""
Returns a string representation of the frame's attributes, if any.
"""
return ', '.join([attrnm + '=' + str(getattr(self, attrnm))
for attrnm in self.get_frame_attr_names()])
def __getitem__(self, view):
if self.has_data:
out = self.realize_frame(self.data[view])
out.representation = self.representation
return out
else:
raise ValueError('Cannot index a frame with no data')
@override__dir__
def __dir__(self):
"""
Override the builtin `dir` behavior to include representation
names.
TODO: dynamic representation transforms (i.e. include cylindrical et al.).
"""
dir_values = set(self.representation_component_names)
return dir_values
def __getattr__(self, attr):
"""
Allow access to attributes defined in
``self.representation_component_names``.
TODO: dynamic representation transforms (i.e. include cylindrical et
al.).
"""
# attr == '_representation' is likely from the hasattr() test in the
# representation property which is used for
# self.representation_component_names.
#
# Prevent infinite recursion here.
if (attr == '_representation' or
attr not in self.representation_component_names):
raise AttributeError("'{0}' object has no attribute '{1}'"
.format(self.__class__.__name__, attr))
elif self._data is None:
# The second clause of the ``or`` above means that
# ``attr in self.representation_component_names``, otherwise we
# would repeat that check here, because we only want to hit this
# clause when the user tried to access one of the representation's
# components
self.data # this raises the "no data" error by design - doing it
# this way means we don't have to replicate the error message here
else:
rep = self.represent_as(self.representation, in_frame_units=True)
val = getattr(rep, self.representation_component_names[attr])
return val
def __setattr__(self, attr, value):
repr_attr_names = set()
if hasattr(self, 'representation_info'):
for representation_attr in self.representation_info.values():
repr_attr_names.update(representation_attr['names'])
if attr in repr_attr_names:
raise AttributeError(
'Cannot set any frame attribute {0}'.format(attr))
else:
super(BaseCoordinateFrame, self).__setattr__(attr, value)
def separation(self, other):
"""
Computes on-sky separation between this coordinate and another.
Parameters
----------
other : `~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 .angle_utilities import angular_separation
from .angles import Angle
self_unit_sph = self.represent_as(UnitSphericalRepresentation)
other_transformed = other.transform_to(self)
other_unit_sph = other_transformed.represent_as(UnitSphericalRepresentation)
# Get the separation as a Quantity, convert to Angle in degrees
sep = angular_separation(self_unit_sph.lon, self_unit_sph.lat,
other_unit_sph.lon, other_unit_sph.lat)
return Angle(sep, unit=u.degree)
def separation_3d(self, other):
"""
Computes three dimensional separation between this coordinate
and another.
Parameters
----------
other : `~astropy.coordinates.BaseCoordinateFrame`
The coordinate system to get the distance 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.
"""
from .distances import Distance
if issubclass(self.data.__class__, UnitSphericalRepresentation):
raise ValueError('This object does not have a distance; cannot '
'compute 3d separation.')
# do this first just in case the conversion somehow creates a distance
other_in_self_system = other.transform_to(self)
if issubclass(other_in_self_system.__class__, UnitSphericalRepresentation):
raise ValueError('The other object does not have a distance; '
'cannot compute 3d separation.')
dx = self.cartesian.x - other_in_self_system.cartesian.x
dy = self.cartesian.y - other_in_self_system.cartesian.y
dz = self.cartesian.z - other_in_self_system.cartesian.z
distval = (dx.value ** 2 + dy.value ** 2 + dz.value ** 2) ** 0.5
return Distance(distval, dx.unit)
@property
def cartesian(self):
"""
Shorthand for a cartesian representation of the coordinates in this
object.
"""
# TODO: if representations are updated to use a full transform graph,
# the representation aliases should not be hard-coded like this
return self.represent_as(CartesianRepresentation, in_frame_units=True)
@property
def spherical(self):
"""
Shorthand for a spherical representation of the coordinates in this object.
"""
# TODO: if representations are updated to use a full transform graph,
# the representation aliases should not be hard-coded like this
return self.represent_as(SphericalRepresentation, in_frame_units=True)
class GenericFrame(BaseCoordinateFrame):
"""
A frame object that can't store data but can hold any arbitrary frame
attributes. Mostly useful as a utility for the high-level class to store
intermediate frame attributes.
Parameters
----------
frame_attrs : dict
A dictionary of attributes to be used as the frame attributes for this
frame.
"""
name = None # it's not a "real" frame so it doesn't have a name
def __init__(self, frame_attrs):
self.frame_attributes = OrderedDict()
for name, default in frame_attrs.items():
self.frame_attributes[name] = FrameAttribute(default)
setattr(self, '_' + name, default)
super(GenericFrame, self).__init__(None)
def __getattr__(self, name):
if '_' + name in self.__dict__:
return getattr(self, '_' + name)
else:
raise AttributeError('no {0}'.format(name))
def __setattr__(self, name, value):
if name in self.get_frame_attr_names():
raise AttributeError("can't set frame attribute '{0}'".format(name))
else:
super(GenericFrame, self).__setattr__(name, value)
# doing this import at the bottom prevents a circular import issue that is
# otherwise present due to EarthLocation needing to import ITRS
from .earth import EarthLocation