SlicedLowLevelWCS

class astropy.wcs.wcsapi.SlicedLowLevelWCS(wcs, slices)

Bases: astropy.wcs.wcsapi.BaseWCSWrapper

A Low Level WCS wrapper which applies an array slice to a WCS.

This class does not modify the underlying WCS object and can therefore drop coupled dimensions as it stores which pixel and world dimensions have been sliced out (or modified) in the underlying WCS and returns the modified results on all the Low Level WCS methods.

Parameters

wcsBaseLowLevelWCS

The WCS to slice.

slicesslice or tuple or int

A valid array slice to apply to the WCS.

Attributes Summary

array_shape	The shape of the data that the WCS applies to as a tuple of length pixel_n_dim in (row, column) order (the convention for arrays in Python).
axis_correlation_matrix	Returns an (world_n_dim, pixel_n_dim) matrix that indicates using booleans whether a given world coordinate depends on a given pixel coordinate.
pixel_axis_names	An iterable of strings describing the name for each pixel axis.
pixel_bounds	The bounds (in pixel coordinates) inside which the WCS is defined, as a list with pixel_n_dim (min, max) tuples.
pixel_n_dim	The number of axes in the pixel coordinate system.
pixel_shape	The shape of the data that the WCS applies to as a tuple of length pixel_n_dim in (x, y) order (where for an image, x is the horizontal coordinate and y is the vertical coordinate).
world_axis_names	An iterable of strings describing the name for each world axis.
world_axis_object_classes	A dictionary giving information on constructing high-level objects for the world coordinates.
world_axis_object_components	A list with world_n_dim elements giving information on constructing high-level objects for the world coordinates.
world_axis_physical_types	An iterable of strings describing the physical type for each world axis.
world_axis_units	An iterable of strings given the units of the world coordinates for each axis.
world_n_dim	The number of axes in the world coordinate system.

Methods Summary

pixel_to_world_values(*pixel_arrays)	Convert pixel coordinates to world coordinates.
world_to_pixel_values(*world_arrays)	Convert world coordinates to pixel coordinates.

Attributes Documentation

array_shape

axis_correlation_matrix

pixel_axis_names

pixel_bounds

pixel_n_dim

pixel_shape

world_axis_names

world_axis_object_classes

world_axis_object_components

world_axis_physical_types

world_axis_units

world_n_dim

Methods Documentation

pixel_to_world_values(*pixel_arrays)

Convert pixel coordinates to world coordinates.

This method takes pixel_n_dim scalars or arrays as input, and pixel coordinates should be zero-based. Returns world_n_dim scalars or arrays in units given by world_axis_units. Note that pixel coordinates are assumed to be 0 at the center of the first pixel in each dimension. If a pixel is in a region where the WCS is not defined, NaN can be returned. The coordinates should be specified in the (x, y) order, where for an image, x is the horizontal coordinate and y is the vertical coordinate.

If world_n_dim is 1, this method returns a single scalar or array, otherwise a tuple of scalars or arrays is returned.

world_to_pixel_values(*world_arrays)

Convert world coordinates to pixel coordinates.

This method takes world_n_dim scalars or arrays as input in units given by world_axis_units. Returns pixel_n_dim scalars or arrays. Note that pixel coordinates are assumed to be 0 at the center of the first pixel in each dimension. If a world coordinate does not have a matching pixel coordinate, NaN can be returned. The coordinates should be returned in the (x, y) order, where for an image, x is the horizontal coordinate and y is the vertical coordinate.

If pixel_n_dim is 1, this method returns a single scalar or array, otherwise a tuple of scalars or arrays is returned.