ExtraCoords

class ndcube.ExtraCoords(ndcube=None)[source]

Bases: ndcube.extra_coords.extra_coords.ExtraCoordsABC

A representation of additional world coordinates associated with pixel axes.

ExtraCoords can be initialised by either specifying a LowLevelWCS object and a mapping, or it can be built up by specifying one or more lookup tables.

Parameters

  • wcs – The WCS specifying the extra coordinates.

  • mapping – The mapping between the array dimensions and pixel dimensions in the extra coords object. This is an iterable of (array_dimension, pixel_dimension) pairs of length equal to the number of pixel dimensions in the extra coords.

Attributes Summary

dropped_world_dimensions

Return an APE-14 like representation of any sliced out world dimensions.

mapping

The mapping between the array dimensions and pixel dimensions.

wcs

A WCS object representing the world coordinates described by this ExtraCoords.

Methods Summary

add(name, array_dimension, lookup_table, …)

Add a coordinate to this ExtraCoords based on a lookup table.

from_lookup_tables(names, pixel_dimensions, …)

Construct an ExtraCoords instance from lookup tables.

keys()

The world axis names for all the coordinates in the extra coords.

Attributes Documentation

dropped_world_dimensions

Return an APE-14 like representation of any sliced out world dimensions.

mapping
wcs

Methods Documentation

add(name, array_dimension, lookup_table, **kwargs)[source]

Add a coordinate to this ExtraCoords based on a lookup table.

Parameters

  • name – The name for these world coordinate(s).

  • array_dimension – The pixel dimension(s), in the array, to which this lookup table corresponds.

  • lookup_table – The lookup table. Note, if this table is multi-dimensional it must (currently) be specified with its axes in world order, so transposed with respect to the data array.

classmethod from_lookup_tables(names, pixel_dimensions, lookup_tables)[source]

Construct an ExtraCoords instance from lookup tables.

This is a convience wrapper around add which does not expose all the options available in that method.

Parameters

  • array_shape (tuple of int, optional) – The shape of the array.

  • names (tuple of str) – The names of the world coordinates.

  • pixel_dimensions (tuple of int) – The pixel dimensions (in the array) to which the lookup_tables apply. Must be the same length as lookup_tables.

  • lookup_tables (tuple of object) – The lookup tables which specify the world coordinates for the pixel_dimensions.

Returns

Return type

ndcube.extra_coords.ExtraCoords

keys()[source]

The world axis names for all the coordinates in the extra coords.