QuantityAttribute¶

class astropy.coordinates.QuantityAttribute(default=None, secondary_attribute='', unit=None, shape=None)[source]¶

A frame attribute that is a quantity with specified units and shape (optionally).

Can be None, which should be used for special cases in associated frame transformations like “this quantity should be ignored” or similar.

Parameters:

defaultnumber or Quantity or python:None, optional: Default value for the attribute if the user does not supply one. If a Quantity, it must be consistent with unit, or if a value, unit cannot be None.
secondary_attributepython:str, optional: Name of a secondary instance attribute which supplies the value if default is None and no value was supplied during initialization.
unitastropy:unit-like or python:None, optional: Name of a unit that the input will be converted into. If None, no unit-checking or conversion is performed
shapepython:tuple or python:None, optional: If given, specifies the shape the attribute must be

Methods Summary

Checks that the input is a Quantity with the necessary units (or the special value 0).

Methods Documentation

convert_input(value)[source]¶

Checks that the input is a Quantity with the necessary units (or the special value 0).

Parameters:

Returns:

out, convertedcorrectly-typed object, bool: Tuple consisting of the correctly-typed object and a boolean which indicates if conversion was actually performed.

Raises: