CoordinateTransform

class astropy.coordinates.CoordinateTransform(fromsys, tosys, priority=1, register_graph=None)

Bases: object

An object that transforms a coordinate from one system to another. Subclasses must implement __call__ with the provided signature. They should also call this superclass’s __init__ in their __init__.

Parameters:

fromsys : class

The coordinate frame class to start from.

tosys : class

The coordinate frame class to transform into.

priority : number

The priority if this transform when finding the shortest coordinate transform path - large numbers are lower priorities.

register_graph : TransformGraph or None

A graph to register this transformation with on creation, or None to leave it unregistered.

Methods Summary

Methods Documentation

__call__(fromcoord, toframe)

Does the actual coordinate transformation from the fromsys class to the tosys class.

Parameters:

fromcoord : fromsys object

An object of class matching fromsys that is to be transformed.

toframe : object

An object that has the attributes necessary to fully specify the frame. That is, it must have attributes with names that match the keys of the dictionary that tosys.get_frame_attr_names() returns. Typically this is of class tosys, but it might be some other class as long as it has the appropriate attributes.

Returns:

tocoord : tosys object

The new coordinate after the transform has been applied.

register(graph)

Add this transformation to the requested Transformation graph, replacing anything already connecting these two coordinates.

Parameters:

graph : a TransformGraph object

The graph to register this transformation with.

unregister(graph)

Remove this transformation from the requested transformation graph.

Parameters:

graph : a TransformGraph object

The graph to unregister this transformation from.

Raises:

ValueError

If this is not currently in the transform graph.