skyWcs.py

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# This file is part of afw.
#
# Developed for the LSST Data Management System.
# This product includes software developed by the LSST Project
# (https://www.lsst.org).
# See the COPYRIGHT file at the top-level directory of this distribution
# for details of code ownership.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
import numpy as np
 
from lsst.utils import continueClass
from ._python import reduceTransform
from ._geom import (SkyWcs, makeCdMatrix, makeFlippedWcs, makeModifiedWcs,
                    makeSkyWcs, makeTanSipWcs, makeWcsPairTransform,
                    getIntermediateWorldCoordsToSky, getPixelToIntermediateWorldCoords)
 
__all__ = ["SkyWcs", "makeCdMatrix", "makeFlippedWcs", "makeSkyWcs",
           "makeModifiedWcs", "makeTanSipWcs", "makeWcsPairTransform",
           "getIntermediateWorldCoordsToSky", "getPixelToIntermediateWorldCoords"]
 
 
@continueClass  # noqa: F811 (FIXME: remove for py 3.8+)
class SkyWcs:  # noqa: F811
    def pixelToSkyArray(self, x, y, degrees=False):
        """
        Convert numpy array pixels (x, y) to numpy array sky (ra, dec)
        positions.
 
        Parameters
        ----------
        x : `np.ndarray`
            Array of x values.
        y : `np.ndarray`
            Array of y values.
        degrees : `bool`, optional
            Return ra, dec arrays in degrees if True.
 
        Returns
        -------
        ra : `np.ndarray`
            Array of Right Ascension.  Units are radians unless
            degrees=True.
        dec : `np.ndarray`
            Array of Declination.  Units are radians unless
            degrees=True.
        """
        xy = np.vstack((x, y))
        ra, dec = np.vsplit(self.getTransform().getMapping().applyForward(xy), 2)
        ra %= (2.*np.pi)
 
        if degrees:
            return np.rad2deg(ra.ravel()), np.rad2deg(dec.ravel())
        else:
            return ra.ravel(), dec.ravel()
 
    def skyToPixelArray(self, ra, dec, degrees=False):
        """
        Convert numpy array sky (ra, dec) positions to numpy array
        pixels (x, y).
 
        Parameters
        ----------
        ra : `np.ndarray`
            Array of Right Ascension.  Units are radians unless
            degrees=True.
        dec : `np.ndarray`
            Array of Declination.  Units are radians unless
            degrees=True.
        degrees : `bool`, optional
            Input ra, dec arrays are degrees if True.
 
        Returns
        -------
        x : `np.ndarray`
            Array of x values.
        y : `np.ndarray`
            Array of y values.
        """
        radec = np.vstack((ra, dec))
        if degrees:
            radec = np.deg2rad(radec)
 
        x, y = np.vsplit(self.getTransform().getMapping().applyInverse(radec), 2)
 
        return x.ravel(), y.ravel()
 
 
SkyWcs.__reduce__ = reduceTransform