add unit test code for new InstCatTrimmer; delete unused GsObjectDict…

… class

python/desc/imsim/imSim.py

@@ -536,45 +536,6 @@ def parsePhoSimInstanceFile(fileName, sensor_list, numRows=None):
                                          ([], gs_object_dict))
 
 
-class GsObjectDict:
-    """
-    Dictionary-like class to provide access to lists of
-    GalSimCelestialObjects from an instance catalog on a per-sensor
-    basis.  This class uses InstCatTrimmer to downselect the object
-    entries via acceptance cones centered on the sensor of interest
-    and to defer the creation of the GalSimCelestialObjects until
-    the data for the specified sensor are requested.
-    """
-    def __init__(self, instcat_trimmer, phot_params, radius=0.18):
-        """
-        Parameters
-        ----------
-        instcat_trimmer: InstCatTrimmer
-            This object manages the GalSimCelestialObject creation.
-        phot_params: PhotometricParameters
-            Photometric parameter info for the visit.
-        radius: float [0.18]
-            Acceptance cone radius, in degrees, for downselecting objects
-            for a single CCD.
-        """
-        self.instcat_trimmer = instcat_trimmer
-        self.phot_params = phot_params
-        self.radius = radius
-
-    def __iter__(self):
-        for detector in self.instcat_trimmer._camera:
-            yield detector.getName()
-
-    def __getitem__(self, chip_name):
-        object_lines \
-            = self.instcat_trimmer.get_object_entries(chip_name,
-                                                      radius=self.radius)
-        obs_md = self.instcat_trimmer.obs_md
-        file_name = self.instcat_trimmer.instcat_file
-        return GsObjectList(object_lines, obs_md, self.phot_params, file_name,
-                            chip_name=chip_name)
-
-
 class GsObjectList:
     """
     List-like class to provide access to lists of objects from an

python/desc/imsim/trim.py

@@ -1,6 +1,7 @@
 """
 Function to apply chip-centered acceptance cones on instance catalogs.
 """
+from collections import defaultdict
 import numpy as np
 import lsst.sims.coordUtils
 from lsst.sims.utils import _angularSeparation
@@ -94,31 +95,22 @@ def get_object_entries(self, chip_name, radius=0.18, sort_magnorm=True):
 
         Returns
         -------
-        list: list of object entries from the original instance catalog.
+        list, int: (list of object entries from the original instance catalog,
+                    number of sersic objects for minsource application)
 
-        Notes
-        -----
-        This function applies the 'minsource' criterion to the sersic
-        galaxies in the instance catalog if 'minsource' is included in
-        the instance catalog commands.
         """
         ra0, dec0 = self.compute_chip_center(chip_name)
         seps = degrees_separation(ra0, dec0, self._ra, self._dec)
         index = np.where(seps < radius)
 
-        if (self.trimmer.minsource is not None and
-                sum(self._sersic[index]) < self.trimmer.minsource):
-            # Apply the minsource criterion.
-            return []
-
         # Collect the selected objects.
         selected = [self.object_lines[i] for i in index[0]]
         if sort_magnorm:
             # Sort by magnorm.
             sorted_index = np.argsort(self._magnorm[index])
             selected = [selected[i] for i in sorted_index]
 
-        return selected
+        return selected, sum(self._sersic[index])
 
 class InstCatTrimmer(dict):
     """
@@ -137,7 +129,7 @@ class InstCatTrimmer(dict):
 
     """
     def __init__(self, instcat, sensor_list, chunk_size=int(3e5),
-                 radius=0.18, numRows=None):
+                 radius=0.18, numRows=None, minsource=None):
         """
         Parameters
         ----------
@@ -155,10 +147,15 @@ def __init__(self, instcat, sensor_list, chunk_size=int(3e5),
             sensor.
         numRows: int [None]
             Maximum number of rows to read in from the instance catalog.
+        minsource: int [None]
+            Minimum number of galaxies in a given sensor acceptance cone.
+            If not None, this overrides the value in the instance catalog.
         """
         super(InstCatTrimmer, self).__init__()
         self.instcat_file = instcat
         self._read_commands()
+        if minsource is not None:
+            self.minsource = minsource
         self._process_objects(sensor_list, chunk_size, radius=radius,
                               numRows=numRows)
 
@@ -170,23 +167,30 @@ def _process_objects(self, sensor_list, chunk_size, radius=0.18,
         for each sensor using the Disaggregator class to apply the
         acceptance cone cut centered on each sensor.
         """
+        num_gals = defaultdict(lambda: 0)
         self.update({sensor: [] for sensor in sensor_list})
         with desc.imsim.fopen(self.instcat_file, mode='rt') as fd:
             nread = 0
             while numRows is None or nread < numRows:
                 object_lines = []
+                ichunk = 0
                 for ichunk, line in zip(range(chunk_size), fd):
                     nread += 1
                     if not line.startswith('object'):
                         continue
                     object_lines.append(line)
                 disaggregator = Disaggregator(object_lines, self)
                 for sensor in self:
-                    obj_list = disaggregator.get_object_entries(sensor,
-                                                                radius=radius)
+                    obj_list, nsersic = disaggregator\
+                        .get_object_entries(sensor, radius=radius)
                     self[sensor].extend(obj_list)
+                    num_gals[sensor] += nsersic
                 if ichunk < chunk_size - 1:
                     break
+        for sensor in self:
+            # Apply minsource criterion on galaxies.
+            if self.minsource is not None and num_gals[sensor] < self.minsource:
+                self[sensor] = []
 
     def _read_commands(self):
         """Read in the commands from the instance catalog."""

tests/test_trimmer.py

@@ -0,0 +1,39 @@
+"""
+Unit tests for InstCatTrimmer class.
+"""
+import os
+import unittest
+import desc.imsim
+
+
+class InstCatTrimmerTestCase(unittest.TestCase):
+    """
+    TestCase class for InstCatTrimmer.
+    """
+    def setUp(self):
+        pass
+
+    def tearDown(self):
+        pass
+
+    def test_InstCatTrimmer(self):
+        """Unit test for InstCatTrimmer class."""
+        instcat = os.path.join(os.environ['IMSIM_DIR'], 'tests',
+                               'tiny_instcat.txt')
+        sensor = 'R:2,2 S:1,1'
+
+        # Check the application of minsource.
+        objs = desc.imsim.InstCatTrimmer(instcat, [sensor], minsource=10)
+        self.assertEqual(len(objs[sensor]), 24)
+
+        objs = desc.imsim.InstCatTrimmer(instcat, [sensor], minsource=12)
+        self.assertEqual(len(objs[sensor]), 0)
+
+        # Check various values of chunk_size.
+        for chunk_size in (5, 10, 100):
+            objs = desc.imsim.InstCatTrimmer(instcat, [sensor], minsource=None,
+                                             chunk_size=chunk_size)
+            self.assertEqual(len(objs[sensor]), 24)
+
+if __name__ == '__main__':
+    unittest.main()