BaseRepresentationOrDifferential

class astropy.coordinates.BaseRepresentationOrDifferential(*args, **kwargs)

Bases: ShapedLikeNDArray

3D coordinate representations and differentials.

Parameters:

comp1, comp2, comp3Quantity or subclass

The components of the 3D point or differential. The names are the keys and the subclasses the values of the attr_classes attribute.

copybool, optional

If True (default), arrays will be copied; if False, they will be broadcast together but not use new memory.

Attributes Summary

components	A tuple with the in-order names of the coordinate components.
info	Container for meta information like name, description, format.
shape	The shape of the instance and underlying arrays.

Methods Summary

from_cartesian(other)	Create a representation of this class from a supplied Cartesian one.
get_name()	Name of the representation or differential.
to_cartesian()	Convert the representation to its Cartesian form.

Attributes Documentation

components

A tuple with the in-order names of the coordinate components.

info

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.

shape

The shape of the instance and underlying arrays.

Like shape, can be set to a new shape by assigning a tuple. Note that if different instances share some but not all underlying data, setting the shape of one instance can make the other instance unusable. Hence, it is strongly recommended to get new, reshaped instances with the reshape method.

Raises:

ValueError

If the new shape has the wrong total number of elements.

AttributeError

If the shape of any of the components cannot be changed without the arrays being copied. For these cases, use the reshape method (which copies any arrays that cannot be reshaped in-place).

Methods Documentation

abstract classmethod from_cartesian(other)

Create a representation of this class from a supplied Cartesian one.

Parameters:

otherCartesianRepresentation

The representation to turn into this class

Returns:

representationBaseRepresentation subclass instance

A new representation of this class’s type.

classmethod get_name()

Name of the representation or differential.

In lower case, with any trailing ‘representation’ or ‘differential’ removed. (E.g., ‘spherical’ for SphericalRepresentation or SphericalDifferential.)

abstract to_cartesian()

Convert the representation to its Cartesian form.

Note that any differentials get dropped. Also note that orientation information at the origin is not preserved by conversions through Cartesian coordinates. For example, transforming an angular position defined at distance=0 through cartesian coordinates and back will lose the original angular coordinates:

>>> import astropy.units as u
>>> import astropy.coordinates as coord
>>> rep = coord.SphericalRepresentation(
...     lon=15*u.deg,
...     lat=-11*u.deg,
...     distance=0*u.pc)
>>> rep.to_cartesian().represent_as(coord.SphericalRepresentation)
<SphericalRepresentation (lon, lat, distance) in (rad, rad, pc)
    (0., 0., 0.)>

Returns:

cartreprCartesianRepresentation

The representation in Cartesian form.