Add refcat selection config option and test

This required modifying the basic catalog loading test, because the selector
might cause a catalog copy, even if it does no selection.

python/lsst/jointcal/jointcal.py

@@ -35,7 +35,7 @@
 from lsst.pipe.tasks.colorterms import ColortermLibrary
 from lsst.verify import Job, Measurement
 
-from lsst.meas.algorithms import LoadIndexedReferenceObjectsTask
+from lsst.meas.algorithms import LoadIndexedReferenceObjectsTask, ReferenceSourceSelectorTask
 from lsst.meas.algorithms.sourceSelector import sourceSelectorRegistry
 
 from .dataIds import PerTractCcdDataIdContainer
@@ -281,6 +281,10 @@ class JointcalConfig(pexConfig.Config):
         doc="How to select sources for cross-matching",
         default="astrometry"
     )
+    referenceSelector = pexConfig.ConfigurableField(
+        target=ReferenceSourceSelectorTask,
+        doc="How to down-select the loaded reference catalog.",
+    )
     writeInitMatrix = pexConfig.Field(
         dtype=bool,
         doc="Write the pre/post-initialization Hessian and gradient to text files, for debugging."
@@ -337,6 +341,7 @@ def __init__(self, butler=None, profile_jointcal=False, **kwargs):
         pipeBase.CmdLineTask.__init__(self, **kwargs)
         self.profile_jointcal = profile_jointcal
         self.makeSubtask("sourceSelector")
+        self.makeSubtask("referenceSelector")
         if self.config.doAstrometry:
             self.makeSubtask('astrometryRefObjLoader', butler=butler)
         else:
@@ -638,11 +643,12 @@ def _load_reference_catalog(self, refObjLoader, center, radius, filterName,
                                                afwGeom.Angle(radius, afwGeom.radians),
                                                filterName)
 
+        selected = self.referenceSelector.run(skyCircle.refCat)
         # Need memory contiguity to get reference filters as a vector.
-        if not skyCircle.refCat.isContiguous():
-            refCat = skyCircle.refCat.copy(deep=True)
+        if not selected.sourceCat.isContiguous():
+            refCat = selected.sourceCat.copy(deep=True)
         else:
-            refCat = skyCircle.refCat
+            refCat = selected.sourceCat
 
         if applyColorterms:
             try:

tests/test_jointcal.py

@@ -162,7 +162,29 @@ def test_load_reference_catalog(self):
                                                                   center,
                                                                   radius,
                                                                   filterName)
-        self.assertEqual(refCat, fakeRefCat)
+        # operator== isn't implemented for Catalogs, so we have to check like
+        # this, in case the records are copied during load.
+        self.assertEqual(len(refCat), len(fakeRefCat))
+        for r1, r2 in zip(refCat, fakeRefCat):
+            self.assertEqual(r1, r2)
+
+    def test_load_reference_catalog_subselect(self):
+        """Test that we can select out the one source in the fake refcat
+        with a ridiculous S/N cut.
+        """
+        refObjLoader, center, radius, filterName, fakeRefCat = self._make_fake_refcat()
+
+        config = lsst.jointcal.jointcal.JointcalConfig()
+        config.doAstrometry = False
+        config.doPhotometry = False
+        config.referenceSelector.doSignalToNoise = True
+        config.referenceSelector.signalToNoise.minimum = 1e10
+        config.referenceSelector.signalToNoise.fluxField = "fake_flux"
+        config.referenceSelector.signalToNoise.errField = "fake_fluxErr"
+        jointcal = lsst.jointcal.JointcalTask(config=config)
+
+        refCat, fluxField = jointcal._load_reference_catalog(refObjLoader, center, radius, filterName)
+        self.assertEqual(len(refCat), 0)
 
 
 class MemoryTester(lsst.utils.tests.MemoryTestCase):