tools

A collection of helper functions to support pysiaf calculations and functionalities.

Authors

• Johannes Sahlmann

pysiaf.utils.tools.an_to_tel(xan_arcsec, yan_arcsec)

Convert from XAN, YAN to V2, V3.

pysiaf.utils.tools.compute_roundtrip_error(A, B, C, D, offset_x=0.0, offset_y=0.0, verbose=False, instrument='', grid_amplitude=None)

Return the roundtrip error of the distortion transformations specified by A,B,C,D.

Test whether the forward and inverse idl-sci transformations are consistent.

Parameters:

Anumpy array

polynomial coefficients

Bnumpy array

polynomial coefficients

Cnumpy array

polynomial coefficients

Dnumpy array

polynomial coefficients

offset_xfloat

Offset subtracted from input coordinate

offset_yfloat

Offset subtracted from input coordinate

verbosebool

verbosity

instrumentstr

Instrument name

Returns:

error_estimation_metric, dx.mean(), dy.mean(), dx.std(), dy.std(), datatuple

mean and std of errors, data used in computations

pysiaf.utils.tools.convert_polynomial_coefficients(A_in, B_in, C_in, D_in, oss=False, inverse=False, parent_aperture=None)

Emulate some transformation made in nircam_get_polynomial_both.

Written by Johannes Sahlmann 2018-02-18, structure largely based on nircamtrans.py code by Colin Cox.

Parameters:

A_innumpy array

polynomial coefficients

B_innumpy array

polynomial coefficients

C_innumpy array

polynomial coefficients

D_innumpy array

polynomial coefficients

ossbool

Whether this is an OSS aperture or not

inversebool

Whether this is forward or backward/inverse transformation

parent_aperturestr

Name of parent aperture

Returns:

AR, BR, CR, DR, V3SciXAngle, V3SciYAngle, V2Ref, V3Reftuple of arrays and floats

Converted polynomial coefficients

pysiaf.utils.tools.correct_V3SciXAngle(V3SciXAngle_deg)

Correct input angle.

Parameters:

V3SciXAngle_deg

Returns:

V3SciXAngle_degfloat

pysiaf.utils.tools.correct_V3SciYAngle(V3SciYAngle_deg)

Correct input angle.

Parameters:

V3SciYAngle_deg

Returns:

V3SciYAngle_deg_correctedfloat

pysiaf.utils.tools.get_grid_coordinates(n_side, centre, x_width, y_width=None, max_radius=None)

Return tuple of arrays that contain the coordinates on a regular grid.

Parameters:

n_side: int

Number of points per side. The returned arrays have n_side**2 entries.

centre: tuple of floats

Center coordinate

x_width: float

Extent of the grid in the first dimension

t_width: float

Extent of the grid in the second dimension

Returns:

xarray

yarray

pysiaf.utils.tools.is_ipython()

Function that returns True if the user is in an ipython session and False if they are not

pysiaf.utils.tools.jwst_fgs_to_fgs_matrix(direction='fgs2_to_fgs1', siaf=None, verbose=False)

Return JWST FGS1_OSS to FGS2_OSS transformation matrix as stored in LoadsPRD.

Parameters:

siafpysiaf.Siaf instance

JWST FGS SIAF content

Returns:

R12ndarray

rotation matrix

References

pysiaf.utils.tools.match_v2v3(aperture_1, aperture_2, verbose=False, match_v2_only=False)

Modify the X[Y]DetRef,X[Y]SciRef attributes of aperture_2 such that V2Ref,V3Ref of both apertures match.

Also shift the polynomial coefficients to reflect the new reference point origin and for NIRCam recalculate angles.

Parameters:

aperture_1pysiaf.Aperture object

Aperture whose V2,V3 reference position is to be used

aperture_2pysiaf.Aperture object

The V2,V3 reference position is to be altered to match that of aperture_1

verbosebool

verbosity

Returns:

new_aperture_2: pysiaf.Aperture object

An aperture object derived from aperture_2 but with some parameters changed to match altered V2V3.

pysiaf.utils.tools.revert_correct_V3SciXAngle(V3SciXAngle_deg)

Return corrected V3SciXAngle.

Parameters:

V3SciXAngle_degfloat

Angle in deg

Returns:

V3SciXAngle_degfloat

Angle in deg

pysiaf.utils.tools.revert_correct_V3SciYAngle(V3SciYAngle_deg)

Return corrected V3SciYAngle.

Only correct if the original V3SciYAngle in [0,180) deg

Parameters:

V3SciYAngle_degfloat

angle in deg

Returns:

V3SciYAngle_degfloat

Angle in deg

pysiaf.utils.tools.set_reference_point_and_distortion(instrument, aperture, parent_aperture)

Set V2Ref and V3ref and distortion coefficients for an aperture with a parent_aperture.

Parameters:

instrumentstr

Instrument name

aperturepysiaf.Aperture object

Aperture

parent_aperturepysiaf.Aperture object

Parent aperture

pysiaf.utils.tools.tel_to_an(v2_arcsec, v3_arcsec)

Convert from V2, V3 to XAN, YAN.

pysiaf.utils.tools.v3sciyangle_to_v3idlyangle(v3sciyangle)

Convert V3SciYAngle to V3IdlYAngle.

Parameters:

v3sciyanglefloat

angle

Returns:

v3sciyanglefloat

angle

pysiaf.utils.tools.write_matrix_to_file(matrix, file, comments=None, format='jwst_fsw_patch_request')

Write the elements of a matrix to a text file.

Parameters:

matrixndarray

the matrix

filestr

output file name

commentsdict

comments to include in the commented file header

formatstr

Formatting of matrix elements in output