Add updateRefCentroids and updateSourceCoords

Add two utility functions to lsst.afw.table:
updateRefCentroids and updateSourceCoords.
Add a unit test for these functions testTableUtils.py
(since the functions are defined in new module lsst.afw.table.utils)

python/lsst/afw/table/__init__.py

@@ -2,3 +2,4 @@
 from .tableEnumDicts import *
 from .multiMatch import *
 from .catalogMatches import *
+from .utils import *

python/lsst/afw/table/utils.py

@@ -0,0 +1,69 @@
+#
+# LSST Data Management System
+# Copyright 2016 AURA/LSST.
+#
+# This product includes software developed by the
+# LSST Project (http://www.lsst.org/).
+#
+# 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 LSST License Statement and
+# the GNU General Public License along with this program.  If not,
+# see <https://www.lsstcorp.org/LegalNotices/>.
+#
+from __future__ import absolute_import, division, print_function
+
+from .tableLib import CoordKey, Point2DKey
+
+__all__ = ["updateRefCentroids", "updateSourceCoords"]
+
+
+def updateRefCentroids(wcs, refList):
+    """Update centroids in a collection of reference objects
+
+    This code supports any kind of collection, instead of requiring a catalog,
+    to make it easy to use with match lists. For example:
+
+        updateRefCentroids(wcs, refList=[match.first for match in matches])
+
+    @param[in] wcs  WCS to map from sky to pixels; an lsst.afw.image.Wcs
+    @param[in,out] refList  collection of reference objects (lsst.afw.table.SimpleRecords) with fields:
+                            - "coord", a field of lsst.afw.coord.Coord, is read
+                            - "centroid", a field of lsst.afw.geom.Point2D, is written
+    """
+    if len(refList) < 1:
+        return
+    schema = refList[0].schema
+    coordKey = CoordKey(schema["coord"])
+    centroidKey = Point2DKey(schema["centroid"])
+    for refObj in refList:
+        refObj.set(centroidKey, wcs.skyToPixel(refObj.get(coordKey)))
+
+
+def updateSourceCoords(wcs, sourceList):
+    """Update coords in a collection of sources
+
+    This code supports any kind of collection, instead of requiring a catalog,
+    to make it easy to use with match lists. For example:
+
+        updateSourceCoords(wcs, sourceList=[match.second for match in matches])
+
+    @param[in] wcs  WCS to map from pixels to sky; an lsst.afw.image.Wcs
+    @param[in,out] sourceList    collection of sources (lsst.afw.table.SourceRecords) with fields:
+                                - "slot_Centroid" (as returned by getCentroid) is read
+                                - "coord", a field of lsst.afw.coord.Coord, is written
+    """
+    if len(sourceList) < 1:
+        return
+    schema = sourceList[0].schema
+    srcCoordKey = CoordKey(schema["coord"])
+    for src in sourceList:
+        src.set(srcCoordKey, wcs.pixelToSky(src.getCentroid()))

tests/testTableUtils.py

@@ -0,0 +1,181 @@
+#!/usr/bin/env python
+
+# LSST Data Management System
+# Copyright 2016 LSST Corporation.
+#
+# This product includes software developed by the
+# LSST Project (http://www.lsst.org/).
+#
+# 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 LSST License Statement and
+# the GNU General Public License along with this program.  If not,
+# see <http://www.lsstcorp.org/LegalNotices/>.
+#
+# The classes in this test are a little non-standard to reduce code
+# duplication and support automated unittest discovery.
+# A base class includes all the code that implements the testing and
+# itself inherits from unittest.TestCase. unittest automated discovery
+# will scan all classes that inherit from unittest.TestCase and invoke
+# any test methods found. To prevent this base class from being executed
+# the test methods are placed in a different class that does not inherit
+# from unittest.TestCase. The actual test classes then inherit from
+# both the testing class and the implementation class allowing test
+# discovery to only run tests found in the subclasses.
+
+from __future__ import absolute_import, division, print_function
+import math
+import unittest
+from itertools import izip
+
+import numpy as np
+
+import lsst.utils.tests
+import lsst.afw.coord as afwCoord
+import lsst.afw.geom as afwGeom
+import lsst.afw.image as afwImage
+import lsst.afw.table as afwTable
+
+
+def setup_module(module):
+    lsst.utils.tests.init()
+
+
+def setCentroids(cat, key, maxPix, numPoints):
+    """Add a square grid of points to an empty catalog
+
+    The catalog must be empty to start with
+
+    @param[in,out] cat  a catalog, e.g. lsst.afw.table.SimpleCatalog
+    @paramp[in] key  key for field to be set
+    @param[in] maxPix  maximum pixel position; used for both x and y;
+                        the min is the negative of maxPix
+    @param[in] numPoints  number of points in x or y; total points = numPoints*numPoints
+    """
+    if len(cat) != 0:
+        raise RuntimeError("cat must be empty")
+    for i in np.linspace(-maxPix, maxPix, numPoints):
+        for j in np.linspace(-maxPix, maxPix, numPoints):
+            rec = cat.addNew()
+            rec.set(key, afwGeom.Point2D(i, j))
+
+
+class UpdateTestCase(lsst.utils.tests.TestCase):
+    """A test case for the lsst.afw.table.updateRefCentroids and updateSourceCoords
+    """
+
+    def setUp(self):
+        self.crval = afwCoord.IcrsCoord(afwGeom.PointD(44., 45.))
+        self.crpix = afwGeom.Point2D(15000, 4000)
+
+        arcsecPerPixel = 1/3600.0
+        CD11 = arcsecPerPixel
+        CD12 = 0
+        CD21 = 0
+        CD22 = arcsecPerPixel
+
+        self.wcs = afwImage.makeWcs(self.crval, self.crpix, CD11, CD12, CD21, CD22)
+
+        refSchema = afwTable.SimpleTable.makeMinimalSchema()
+        self.refCentroidKey = afwTable.Point2DKey.addFields(refSchema, "centroid", "centroid", "pixels")
+        self.refCoordKey = afwTable.CoordKey(refSchema["coord"])
+        self.refCat = afwTable.SimpleCatalog(refSchema)
+
+        # an alias is required to make src.getCentroid() work;
+        # simply defining a field named "slot_Centroid" doesn't suffice
+        srcSchema = afwTable.SourceTable.makeMinimalSchema()
+        self.srcCentroidKey = afwTable.Point2DKey.addFields(srcSchema, "base_SdssCentroid",
+                                                            "centroid", "pixels")
+        srcAliases = srcSchema.getAliasMap()
+        srcAliases.set("slot_Centroid", "base_SdssCentroid")
+        self.srcCoordKey = afwTable.CoordKey(srcSchema["coord"])
+        self.sourceCat = afwTable.SourceCatalog(srcSchema)
+
+    def tearDown(self):
+        del self.wcs
+        del self.refCat
+        del self.sourceCat
+
+    def testNull(self):
+        """Check that an empty list causes no problems for either function"""
+        afwTable.updateRefCentroids(self.wcs, [])
+        afwTable.updateSourceCoords(self.wcs, [])
+
+    def testRefCenter(self):
+        """Check that a ref obj at the center is handled as expected"""
+        refObj = self.refCat.addNew()
+        refObj.set(self.refCoordKey, self.crval)
+
+        # initial centroid should be nan
+        nanRefCentroid = self.refCat[0].get(self.refCentroidKey)
+        for val in nanRefCentroid:
+            self.assertTrue(math.isnan(val))
+
+        # computed centroid should be crpix
+        afwTable.updateRefCentroids(self.wcs, self.refCat)
+        refCentroid = self.refCat[0].get(self.refCentroidKey)
+        self.assertPairsNearlyEqual(refCentroid, self.crpix)
+
+        # coord should not be changed
+        self.assertPairsNearlyEqual(self.refCat[0].get(self.refCoordKey), self.crval, maxDiff=0)
+
+    def testSourceCenter(self):
+        """Check that a source at the center is handled as expected"""
+        src = self.sourceCat.addNew()
+        src.set(self.srcCentroidKey, self.crpix)
+
+        # initial coord should be nan; as a sanity-check
+        nanSourceCoord = self.sourceCat[0].get(self.srcCoordKey)
+        for val in nanSourceCoord:
+            self.assertTrue(math.isnan(val))
+
+        # compute coord should be crval
+        afwTable.updateSourceCoords(self.wcs, self.sourceCat)
+        srcCoord = self.sourceCat[0].get(self.srcCoordKey)
+        self.assertPairsNearlyEqual(srcCoord, self.crval)
+
+        # centroid should not be changed; also make sure that getCentroid words
+        self.assertPairsNearlyEqual(self.sourceCat[0].getCentroid(), self.crpix, maxDiff=0)
+
+    def testList(self):
+        """Check lists of reference objects and sources"""
+        maxPix = 1000
+        numPoints = 10
+        setCentroids(cat=self.sourceCat, key=self.srcCentroidKey, maxPix=maxPix, numPoints=numPoints)
+        for src in self.sourceCat:
+            refObj = self.refCat.addNew()
+            centroid = src.get(self.srcCentroidKey)
+            coord = self.wcs.pixelToSky(centroid)
+            refObj.setCoord(coord)
+        self.assertEqual(len(self.sourceCat), len(self.refCat))
+
+        # update the catalogs, but this time use a list instead of an actual catalog
+        # to make sure that feature works
+        afwTable.updateSourceCoords(self.wcs, [s for s in self.sourceCat])
+        afwTable.updateRefCentroids(self.wcs, [r for r in self.refCat])
+
+        # check that centroids and coords match
+        for src, refObj in izip(self.sourceCat, self.refCat):
+            srcCentroid = src.get(self.srcCentroidKey)
+            refCentroid = refObj.get(self.refCentroidKey)
+            self.assertPairsNearlyEqual(srcCentroid, refCentroid)
+
+            srcCoord = src.get(self.srcCoordKey)
+            refCoord = refObj.get(self.refCoordKey)
+            self.assertCoordsNearlyEqual(srcCoord, refCoord)
+
+
+class MyMemoryTestCase(lsst.utils.tests.MemoryTestCase):
+    pass
+
+if __name__ == "__main__":
+    lsst.utils.tests.init()
+    unittest.main()