Allow users to retrieve counts from taxo association facets (#13414)

Add a count field to LabelAndValue

lucene/CHANGES.txt

@@ -274,6 +274,8 @@ New Features
 * GITHUB#13181: Add new VectorScorer interface to vector value iterators. This allows for vector codecs to supply
   simpler and more optimized vector scoring when iterating vector values directly. (Ben Trent)
 
+* GITHUB#13414: Counts are always available in the result when using taxonomy facets. (Stefan Vodita)
+
 Improvements
 ---------------------
 

lucene/demo/src/java/org/apache/lucene/demo/facet/AssociationsFacetsExample.java

@@ -26,6 +26,7 @@ import org.apache.lucene.facet.FacetResult;
 import org.apache.lucene.facet.Facets;
 import org.apache.lucene.facet.FacetsCollector;
 import org.apache.lucene.facet.FacetsConfig;
+import org.apache.lucene.facet.LabelAndValue;
 import org.apache.lucene.facet.taxonomy.AssociationAggregationFunction;
 import org.apache.lucene.facet.taxonomy.FloatAssociationFacetField;
 import org.apache.lucene.facet.taxonomy.IntAssociationFacetField;
@@ -165,5 +166,12 @@ public class AssociationsFacetsExample {
     List<FacetResult> results = new AssociationsFacetsExample().runSumAssociations();
     System.out.println("tags: " + results.get(0));
     System.out.println("genre: " + results.get(1));
+    System.out.println("-------------------------");
+    System.out.println("Counts per label are also available:");
+    for (FacetResult facetResult : results) {
+      for (LabelAndValue lv : facetResult.labelValues) {
+        System.out.println("\t" + lv.label + ": " + lv.count);
+      }
+    }
   }
 }

lucene/facet/src/java/org/apache/lucene/facet/LabelAndValue.java

@@ -24,10 +24,21 @@ public final class LabelAndValue {
   /** Value associated with this label. */
   public final Number value;
 
-  /** Sole constructor. */
+  /** Number of occurrences for this label. */
+  public final int count;
+
+  /** Constructor with unspecified count, we assume the value is a count. */
   public LabelAndValue(String label, Number value) {
     this.label = label;
     this.value = value;
+    this.count = value.intValue();
+  }
+
+  /** Constructor with value and count. */
+  public LabelAndValue(String label, Number value, int count) {
+    this.label = label;
+    this.value = value;
+    this.count = count;
   }
 
   @Override

lucene/facet/src/java/org/apache/lucene/facet/taxonomy/TaxonomyFacets.java

@@ -342,7 +342,9 @@ abstract class TaxonomyFacets extends Facets {
     // add 1 here to also account for the dim:
     int childComponentIdx = path.length + 1;
     for (int i = 0; i < labelValues.length; i++) {
-      labelValues[i] = new LabelAndValue(bulkPath[i].components[childComponentIdx], values[i]);
+      labelValues[i] =
+          new LabelAndValue(
+              bulkPath[i].components[childComponentIdx], values[i], getCount(ordinals[i]));
     }
 
     return new FacetResult(
@@ -418,7 +420,9 @@ abstract class TaxonomyFacets extends Facets {
 
     LabelAndValue[] labelValues = new LabelAndValue[ordValues.size()];
     for (int i = 0; i < ordValues.size(); i++) {
-      labelValues[i] = new LabelAndValue(bulkPath[i].components[cp.length], ordValues.get(i));
+      labelValues[i] =
+          new LabelAndValue(
+              bulkPath[i].components[cp.length], ordValues.get(i), getCount(ordinals.get(i)));
     }
     return new FacetResult(dim, path, aggregatedValue, labelValues, ordinals.size());
   }

lucene/facet/src/test/org/apache/lucene/facet/FacetTestCase.java

@@ -288,4 +288,20 @@ public abstract class FacetTestCase extends LuceneTestCase {
     // assert children equal with no assumption of the children ordering
     assertTrue(Arrays.asList(result.labelValues).containsAll(Arrays.asList(expectedChildren)));
   }
+
+  protected void assertFacetResult(
+      FacetResult result,
+      String expectedDim,
+      String[] expectedPath,
+      int expectedChildCount,
+      Number expectedValue,
+      Map<String, Integer> countPerLabel,
+      LabelAndValue... expectedChildren) {
+    assertFacetResult(
+        result, expectedDim, expectedPath, expectedChildCount, expectedValue, expectedChildren);
+    assertEquals(result.labelValues.length, countPerLabel.size());
+    for (LabelAndValue lv : result.labelValues) {
+      assertEquals(lv.count, (int) countPerLabel.get(lv.label));
+    }
+  }
 }

lucene/facet/src/test/org/apache/lucene/facet/taxonomy/TestTaxonomyFacetAssociations.java

@@ -226,6 +226,7 @@ public class TestTaxonomyFacetAssociations extends FacetTestCase {
         new String[0],
         2,
         -1,
+        Map.of("a", 100, "b", 50),
         new LabelAndValue[] {
           new LabelAndValue("a", 200), new LabelAndValue("b", 150),
         });
@@ -309,6 +310,7 @@ public class TestTaxonomyFacetAssociations extends FacetTestCase {
         new String[0],
         2,
         -1f,
+        Map.of("a", 100, "b", 50),
         new LabelAndValue[] {
           new LabelAndValue("a", 50.0f), new LabelAndValue("b", 9.999995f),
         });