Make classification evaluation metrics work when there is field mapping type mismatch (#53458)

Author: przemekwitek

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/dataframe/evaluation/classification/Accuracy.java

@@ -28,11 +28,9 @@
 import org.elasticsearch.xpack.core.ml.utils.ExceptionsHelper;
 
 import java.io.IOException;
-import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
 
@@ -66,12 +64,6 @@ public class Accuracy implements EvaluationMetric {
 
     static final String OVERALL_ACCURACY_AGG_NAME = "classification_overall_accuracy";
 
-    private static final String PAINLESS_TEMPLATE = "doc[''{0}''].value == doc[''{1}''].value";
-
-    private static Script buildScript(Object...args) {
-        return new Script(new MessageFormat(PAINLESS_TEMPLATE, Locale.ROOT).format(args));
-    }
-
     private static final ObjectParser<Accuracy, Void> PARSER = new ObjectParser<>(NAME.getPreferredName(), true, Accuracy::new);
 
     public static Accuracy fromXContent(XContentParser parser) {
@@ -112,7 +104,8 @@ public final Tuple<List<AggregationBuilder>, List<PipelineAggregationBuilder>> a
         List<AggregationBuilder> aggs = new ArrayList<>();
         List<PipelineAggregationBuilder> pipelineAggs = new ArrayList<>();
         if (overallAccuracy.get() == null) {
-            aggs.add(AggregationBuilders.avg(OVERALL_ACCURACY_AGG_NAME).script(buildScript(actualField, predictedField)));
+            Script script = PainlessScripts.buildIsEqualScript(actualField, predictedField);
+            aggs.add(AggregationBuilders.avg(OVERALL_ACCURACY_AGG_NAME).script(script));
         }
         if (result.get() == null) {
             Tuple<List<AggregationBuilder>, List<PipelineAggregationBuilder>> matrixAggs =

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/dataframe/evaluation/classification/PainlessScripts.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.core.ml.dataframe.evaluation.classification;
+
+import org.elasticsearch.script.Script;
+
+import java.text.MessageFormat;
+import java.util.Locale;
+
+/**
+ * Painless scripts used by classification metrics in this package.
+ */
+final class PainlessScripts {
+
+    /**
+     * Template for the comparison script.
+     * It uses "String.valueOf" method in case the mapping types of the two fields are different.
+     */
+    private static final MessageFormat COMPARISON_SCRIPT_TEMPLATE =
+        new MessageFormat("String.valueOf(doc[''{0}''].value).equals(String.valueOf(doc[''{1}''].value))", Locale.ROOT);
+
+    /**
+     * Builds script that tests field values equality for the given actual and predicted field names.
+     *
+     * @param actualField name of the actual field
+     * @param predictedField name of the predicted field
+     * @return script that tests whether the values of actualField and predictedField are equal
+     */
+    static Script buildIsEqualScript(String actualField, String predictedField) {
+        return new Script(COMPARISON_SCRIPT_TEMPLATE.format(new Object[]{ actualField, predictedField }));
+    }
+}

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/dataframe/evaluation/classification/Precision.java

@@ -34,11 +34,9 @@
 import org.elasticsearch.xpack.core.ml.utils.ExceptionsHelper;
 
 import java.io.IOException;
-import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.stream.Collectors;
@@ -59,17 +57,12 @@ public class Precision implements EvaluationMetric {
 
     public static final ParseField NAME = new ParseField("precision");
 
-    private static final String PAINLESS_TEMPLATE = "doc[''{0}''].value == doc[''{1}''].value";
     private static final String AGG_NAME_PREFIX = "classification_precision_";
     static final String ACTUAL_CLASSES_NAMES_AGG_NAME = AGG_NAME_PREFIX + "by_actual_class";
     static final String BY_PREDICTED_CLASS_AGG_NAME = AGG_NAME_PREFIX + "by_predicted_class";
     static final String PER_PREDICTED_CLASS_PRECISION_AGG_NAME = AGG_NAME_PREFIX + "per_predicted_class_precision";
     static final String AVG_PRECISION_AGG_NAME = AGG_NAME_PREFIX + "avg_precision";
 
-    private static Script buildScript(Object...args) {
-        return new Script(new MessageFormat(PAINLESS_TEMPLATE, Locale.ROOT).format(args));
-    }
-
     private static final ObjectParser<Precision, Void> PARSER = new ObjectParser<>(NAME.getPreferredName(), true, Precision::new);
 
     public static Precision fromXContent(XContentParser parser) {
@@ -116,7 +109,7 @@ public final Tuple<List<AggregationBuilder>, List<PipelineAggregationBuilder>> a
                 topActualClassNames.get().stream()
                     .map(className -> new KeyedFilter(className, QueryBuilders.termQuery(predictedField, className)))
                     .toArray(KeyedFilter[]::new);
-            Script script = buildScript(actualField, predictedField);
+            Script script = PainlessScripts.buildIsEqualScript(actualField, predictedField);
             return Tuple.tuple(
                 List.of(
                     AggregationBuilders.filters(BY_PREDICTED_CLASS_AGG_NAME, keyedFiltersPredicted)

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/dataframe/evaluation/classification/Recall.java

@@ -20,6 +20,7 @@
 import org.elasticsearch.search.aggregations.AggregationBuilder;
 import org.elasticsearch.search.aggregations.AggregationBuilders;
 import org.elasticsearch.search.aggregations.Aggregations;
+import org.elasticsearch.search.aggregations.BucketOrder;
 import org.elasticsearch.search.aggregations.PipelineAggregationBuilder;
 import org.elasticsearch.search.aggregations.PipelineAggregatorBuilders;
 import org.elasticsearch.search.aggregations.bucket.terms.Terms;
@@ -30,11 +31,9 @@
 import org.elasticsearch.xpack.core.ml.utils.ExceptionsHelper;
 
 import java.io.IOException;
-import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
 
@@ -54,16 +53,11 @@ public class Recall implements EvaluationMetric {
 
     public static final ParseField NAME = new ParseField("recall");
 
-    private static final String PAINLESS_TEMPLATE = "doc[''{0}''].value == doc[''{1}''].value";
     private static final String AGG_NAME_PREFIX = "classification_recall_";
     static final String BY_ACTUAL_CLASS_AGG_NAME = AGG_NAME_PREFIX + "by_actual_class";
     static final String PER_ACTUAL_CLASS_RECALL_AGG_NAME = AGG_NAME_PREFIX + "per_actual_class_recall";
     static final String AVG_RECALL_AGG_NAME = AGG_NAME_PREFIX + "avg_recall";
 
-    private static Script buildScript(Object...args) {
-        return new Script(new MessageFormat(PAINLESS_TEMPLATE, Locale.ROOT).format(args));
-    }
-
     private static final ObjectParser<Recall, Void> PARSER = new ObjectParser<>(NAME.getPreferredName(), true, Recall::new);
 
     public static Recall fromXContent(XContentParser parser) {
@@ -98,11 +92,12 @@ public final Tuple<List<AggregationBuilder>, List<PipelineAggregationBuilder>> a
         if (result.get() != null) {
             return Tuple.tuple(List.of(), List.of());
         }
-        Script script = buildScript(actualField, predictedField);
+        Script script = PainlessScripts.buildIsEqualScript(actualField, predictedField);
         return Tuple.tuple(
             List.of(
                 AggregationBuilders.terms(BY_ACTUAL_CLASS_AGG_NAME)
                     .field(actualField)
+                    .order(List.of(BucketOrder.count(false), BucketOrder.key(true)))
                     .size(MAX_CLASSES_CARDINALITY)
                     .subAggregation(AggregationBuilders.avg(PER_ACTUAL_CLASS_RECALL_AGG_NAME).script(script))),
             List.of(

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/dataframe/evaluation/classification/PainlessScriptsTests.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.core.ml.dataframe.evaluation.classification;
+
+import org.elasticsearch.script.Script;
+import org.elasticsearch.test.ESTestCase;
+
+import static org.hamcrest.Matchers.equalTo;
+
+public class PainlessScriptsTests extends ESTestCase {
+
+    public void testBuildIsEqualScript() {
+        Script script = PainlessScripts.buildIsEqualScript("act", "pred");
+        assertThat(script.getIdOrCode(), equalTo("String.valueOf(doc['act'].value).equals(String.valueOf(doc['pred'].value))"));
+    }
+}