DM-11155: Implement object count metrics

python/lsst/ap/association/assoc_db_sqlite.py

@@ -268,8 +268,8 @@ def load(self, expMd):
         ----------
         expMd : lsst.pipe.base.Struct
             A struct object containing:
-               bbox : A lsst.afw.geom.Box2D.
-               wcs : A lsst.afw Wcs object.
+            * bbox : A lsst.afw.geom.Box2D.
+            * wcs : A lsst.afw Wcs object.
 
         Returns
         -------

python/lsst/ap/association/association.py

@@ -118,9 +118,25 @@ def associate_sources(self, dia_collection, dia_sources):
         """
         scores = dia_collection.score(
             dia_sources, self.config.maxDistArcSeconds * afwGeom.arcseconds)
-        updated_dia_objects = dia_collection.match(dia_sources, scores)
+        match_result = dia_collection.match(dia_sources, scores)
+
+        self._add_association_meta_data(match_result)
 
         return pipeBase.Struct(
             dia_collection=dia_collection,
-            updated_ids=updated_dia_objects
+            updated_ids=match_result.updated_and_new_dia_object_ids,
         )
+
+    def _add_association_meta_data(self, match_result):
+        """ Store summaries of the association step in the task metadata.
+
+        Parameters
+        ----------
+        match_result : lsst.pipe.base.Struct
+        """
+        self.metadata.add('numUpdatedDiaObjects',
+                          match_result.n_updated_dia_objects)
+        self.metadata.add('numNewDiaObjects',
+                          match_result.n_new_dia_objects)
+        self.metadata.add('numUnassociatedDiaObjects',
+                          match_result.n_unassociated_dia_objects)

python/lsst/ap/association/dia_collection.py

@@ -263,13 +263,24 @@ def match(self, dia_source_catalog, score_struct):
 
         Returns
         -------
-        Ids of newly updated and created DIAObjects
+        pipeBase.Struct
+            A struct containing the following data:
+            * updated_and_new_dia_object_ids : list of ints specifying the ids
+                new and updated dia_objects in the collection.
+            * n_updated_dia_objects : number of previously know dia_objects with
+               newly associated DIASources.
+            * n_new_dia_objects : Number of newly created DIAObjects from
+                unassociated DIASources
+            * n_unupdated_dia_objects : number of previous DIAObjects that were
+                not associated to a new DIASource.
         """
 
-        used_dia_object = np.zeros(len(self.dia_objects), dtype=np.bool)
+        n_previous_dia_objects = len(self.dia_objects)
+        used_dia_object = np.zeros(n_previous_dia_objects, dtype=np.bool)
         used_dia_source = np.zeros(len(dia_source_catalog), dtype=np.bool)
 
-        updated_and_new_dia_objects = []
+        updated_dia_objects = []
+        new_dia_objects = []
 
         # We sort from best match to worst to effectively perform a
         # "handshake" match where both the DIASources and DIAObjects agree
@@ -290,7 +301,7 @@ def match(self, dia_source_catalog, score_struct):
             used_dia_object[dia_obj_idx] = True
             used_dia_source[score_idx] = True
             updated_obj_id = score_struct.obj_ids[score_idx]
-            updated_and_new_dia_objects.append(updated_obj_id)
+            updated_dia_objects.append(updated_obj_id)
 
             self.dia_objects[dia_obj_idx].append_dia_source(
                 dia_source_catalog[int(score_idx)])
@@ -301,12 +312,20 @@ def match(self, dia_source_catalog, score_struct):
             tmp_src_cat = afwTable.SourceCatalog(dia_source_catalog.schema)
             tmp_src_cat.append(dia_source_catalog[int(src_idx)])
             self.append(DIAObject(tmp_src_cat))
-            updated_and_new_dia_objects.append(
+            new_dia_objects.append(
                 self.dia_objects[-1].id)
 
         # Return the ids of the DIAObjects in this DIAObjectCollection that
         # were updated or newly created.
-        return updated_and_new_dia_objects
+        n_updated_dia_objects = len(updated_dia_objects)
+        n_unassociated_dia_objects = \
+            n_previous_dia_objects - n_updated_dia_objects
+        updated_dia_objects.extend(new_dia_objects)
+        return pipeBase.Struct(
+            updated_and_new_dia_object_ids=updated_dia_objects,
+            n_updated_dia_objects=n_updated_dia_objects,
+            n_new_dia_objects=len(new_dia_objects),
+            n_unassociated_dia_objects=n_unassociated_dia_objects,)
 
     @property
     def is_updated(self):

tests/test_dia_collection.py

@@ -184,8 +184,12 @@ def test_score_and_match(self):
         # except the last DIAObject in this collection which should be
         # newly created during the matching step and contain only one
         # DIASource.
-        updated_ids = obj_collection.match(src_cat, score_struct)
+        match_result = obj_collection.match(src_cat, score_struct)
+        updated_ids = match_result.updated_and_new_dia_object_ids
         self.assertEqual(len(obj_collection.dia_objects), 5)
+        self.assertEqual(match_result.n_updated_dia_objects, 4)
+        self.assertEqual(match_result.n_new_dia_objects, 1)
+        self.assertEqual(match_result.n_unassociated_dia_objects, 0)
 
         for updated_idx, obj_id in enumerate(updated_ids):
             if updated_idx == len(updated_ids) - 1:
@@ -218,12 +222,15 @@ def test_empty_dia_collection(self):
             # to machine noise.
             self.assertTrue(np.isinf(score_struct.scores[src_idx]))
 
-        updated_indices = dia_collection.match(src_cat, score_struct)
-        self.assertEqual(len(updated_indices), 5)
+        match_result = dia_collection.match(src_cat, score_struct)
+        updated_ids = match_result.updated_and_new_dia_object_ids
         self.assertEqual(len(dia_collection.dia_objects), 5)
+        self.assertEqual(match_result.n_updated_dia_objects, 0)
+        self.assertEqual(match_result.n_new_dia_objects, 5)
+        self.assertEqual(match_result.n_unassociated_dia_objects, 0)
 
         for idx, obj_id in enumerate(dia_collection.get_dia_object_ids()):
-            self.assertEqual(obj_id, updated_indices[idx])
+            self.assertEqual(obj_id, updated_ids[idx])
             # We created a new DIAObject in the collection hence the last
             # DIAObject in this collection is new and contains only one
             # DIASource.