Tabprm#
- class astropy.wcs.Tabprm#
Bases:
object
A class to store the information related to tabular coordinates, i.e., coordinates that are defined via a lookup table.
This class can not be constructed directly from Python, but instead is returned from
tab
.Attributes Summary
int array[M]
(read-only) The lengths of the axes of the coordinate array.int
(read-only) Number of tabular coordinate axes.double array[K_M]...[K_2][K_1][M]
The tabular coordinate array.double array[M]
Index values for the reference pixel for each of the tabular coord axes.double array[M]
(read-only) Interpolated indices into the coord array.double array[K_M]...[K_2][2][M]
(read-only)int array[M]
Association between axes.int
(read-only) Total number of coord vectors in the coord array.int array[M]
Interpolated indices into the coordinate array.int array[M]
+1 if monotonically increasing, -1 if decreasing.Methods Summary
Print the contents of the
Tabprm
object to stdout.set
()Allocates memory for work arrays.
Attributes Documentation
- K#
int array[M]
(read-only) The lengths of the axes of the coordinate array.An array of length
M
whose elements record the lengths of the axes of the coordinate array and of each indexing vector.
- M#
int
(read-only) Number of tabular coordinate axes.
- coord#
double array[K_M]...[K_2][K_1][M]
The tabular coordinate array.Has the dimensions:
(K_M, ... K_2, K_1, M)
(see
K
) i.e. with theM
dimension varying fastest so that theM
elements of a coordinate vector are stored contiguously in memory.
- crval#
double array[M]
Index values for the reference pixel for each of the tabular coord axes.
- delta#
double array[M]
(read-only) Interpolated indices into the coord array.Array of interpolated indices into the coordinate array such that Upsilon_m, as defined in Paper III, is equal to (
p0
[m] + 1) + delta[m].
- extrema#
double array[K_M]...[K_2][2][M]
(read-only)An array recording the minimum and maximum value of each element of the coordinate vector in each row of the coordinate array, with the dimensions:
(K_M, ... K_2, 2, M)
(see
K
). The minimum is recorded in the first element of the compressed K_1 dimension, then the maximum. This array is used by the inverse table lookup function to speed up table searches.
- map#
int array[M]
Association between axes.A vector of length
M
that defines the association between axis m in the M-dimensional coordinate array (1 <= m <= M) and the indices of the intermediate world coordinate and world coordinate arrays.When the intermediate and world coordinate arrays contain the full complement of coordinate elements in image-order, as will usually be the case, then
map[m-1] == i-1
for axis i in the N-dimensional image (1 <= i <= N). In terms of the FITS keywords:map[PVi_3a - 1] == i - 1.
However, a different association may result if the intermediate coordinates, for example, only contains a (relevant) subset of intermediate world coordinate elements. For example, if M == 1 for an image with N > 1, it is possible to fill the intermediate coordinates with the relevant coordinate element with
nelem
set to 1. In this casemap[0] = 0
regardless of the value of i.
- nc#
int
(read-only) Total number of coord vectors in the coord array.Total number of coordinate vectors in the coordinate array being the product K_1 * K_2 * … * K_M.
- p0#
int array[M]
Interpolated indices into the coordinate array.Vector of length
M
of interpolated indices into the coordinate array such that Upsilon_m, as defined in Paper III, is equal to(p0[m] + 1) + delta[m]
.
- sense#
int array[M]
+1 if monotonically increasing, -1 if decreasing.A vector of length
M
whose elements indicate whether the corresponding indexing vector is monotonically increasing (+1), or decreasing (-1).
Methods Documentation
- print_contents()#
Print the contents of the
Tabprm
object to stdout. Probably only useful for debugging purposes, and may be removed in the future.To get a string of the contents, use
repr
.
- set()#
Allocates memory for work arrays.
Also sets up the class according to information supplied within it.
Note that this routine need not be called directly; it will be invoked by functions that need it.
- Raises:
MemoryError
Memory allocation failed.
InvalidTabularParametersError
Invalid tabular parameters.