cfdm.core.CoordinateReference

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class cfdm.core.CoordinateReference(coordinates=None, datum=None, coordinate_conversion=None, source=None, copy=True)

Bases: cfdm.core.abstract.container.Container

A coordinate reference construct of the CF data model.

A coordinate reference construct relates the coordinate values of the coordinate system to locations in a planetary reference frame.

The domain of a field construct may contain various coordinate systems, each of which is constructed from a subset of the dimension and auxiliary coordinate constructs. For example, the domain of a four-dimensional field construct may contain horizontal (y-x), vertical (z), and temporal (t) coordinate systems. There may be more than one of each of these, if there is more than one coordinate construct applying to a particular spatiotemporal dimension (for example, there could be both latitude-longitude and y-x projection coordinate systems). In general, a coordinate system may be constructed implicitly from any subset of the coordinate constructs, yet a coordinate construct does not need to be explicitly or exclusively associated with any coordinate system.

A coordinate system of the field construct can be explicitly defined by a coordinate reference construct which relates the coordinate values of the coordinate system to locations in a planetary reference frame and consists of the following:

• References to the dimension coordinate and auxiliary coordinate constructs that define the coordinate system to which the coordinate reference construct applies. Note that the coordinate values are not relevant to the coordinate reference construct, only their properties.

• A definition of a datum specifying the zeroes of the dimension and auxiliary coordinate constructs which define the coordinate system. The datum may be implied by the metadata of the referenced dimension and auxiliary coordinate constructs, or explicitly provided.

• A coordinate conversion, which defines a formula for converting coordinate values taken from the dimension or auxiliary coordinate constructs to a different coordinate system. A coordinate reference construct relates the coordinate values of the field to locations in a planetary reference frame.

New in version (cfdm): 1.7.0

Initialisation

Parameters

coordinates: sequence of str, optional

Identify the related dimension and auxiliary coordinate constructs by their construct identifiers. Ignored if the source parameter is set.

The coordinates may also be set after initialisation with the set_coordinates and set_coordinate methods.

Parameter example:

coordinates=['dimensioncoordinate2']

Parameter example:

coordinates=('dimensioncoordinate0', 'dimensioncoordinate1')

datum: Datum, optional

Set the datum component of the coordinate reference construct. Ignored if the source parameter is set.

The datum may also be set after initialisation with the set_datum method.

coordinate_conversion: CoordinateConversion, optional

Set the coordinate conversion component of the coordinate reference construct. Ignored if the source parameter is set.

The coordinate conversion may also be set after initialisation with the set_coordinate_conversion method.

source: optional

Initialise the coordinates, datum and coordinate conversion from those of source.

Note that if source is a CoordinateReference instance then cfdm.core.CoordinateReference(source=source) is equivalent to source.copy().

copy: bool, optional

If False then do not deep copy input parameters prior to initialisation. By default arguments are deep copied.

Inspection

Attributes

construct_type

Return a description of the construct type.

Coordinates

Methods

del_coordinate	Remove a reference to a coordinate construct.
has_coordinate	Whether a reference to a coordinate construct has been set.
set_coordinate	Set a reference to a coordinate construct.
coordinates	Return all references to coordinate constructs.
clear_coordinates	Remove all references to coordinate constructs.
set_coordinates	Set references to coordinate constructs.

Datum

Methods

del_datum	Remove the datum component.
get_datum	Return the datum component.
set_datum	Set the datum component.

Attributes

datum

Return the datum component.

Coordinate conversion

Methods

del_coordinate_conversion	Remove the coordinate conversion component.
get_coordinate_conversion	Get the coordinate conversion component.
set_coordinate_conversion	Set the coordinate conversion component.

Attributes

coordinate_conversion

Return the coordinate conversion component.

Miscellaneous

Methods

copy	Return a deep copy.

Special

Methods

__deepcopy__

Called by the copy.deepcopy function.

Docstring substitutions

Methods

_docstring_special_substitutions	Return the special docstring substitutions.
_docstring_substitutions	Returns the substitutions that apply to methods of the class.
_docstring_package_depth	Returns the class {{package}} substitutions package depth.
_docstring_method_exclusions	Returns method names excluded in the class substitutions.