Add chiSquareDataSet Stream Evaluator

solr/core/src/java/org/apache/solr/handler/StreamHandler.java

@@ -290,10 +290,11 @@ public class StreamHandler extends RequestHandlerBase implements SolrCoreAware,
         .withFunctionName("sumSq", SumSqEvaluator.class)
         .withFunctionName("akima", AkimaEvaluator.class)
         .withFunctionName("lerp", LerpEvaluator.class)
+        .withFunctionName("chiSquareDataSet", ChiSquareDataSetEvaluator.class)
 
         // Boolean Stream Evaluators
 
-            .withFunctionName("and", AndEvaluator.class)
+        .withFunctionName("and", AndEvaluator.class)
         .withFunctionName("eor", ExclusiveOrEvaluator.class)
         .withFunctionName("eq", EqualToEvaluator.class)
         .withFunctionName("gt", GreaterThanEvaluator.class)

solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/ChiSquareDataSetEvaluator.java

@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.solr.client.solrj.io.eval;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.commons.math3.stat.inference.ChiSquareTest;
+import org.apache.solr.client.solrj.io.Tuple;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+
+
+public class ChiSquareDataSetEvaluator extends RecursiveNumericListEvaluator implements TwoValueWorker {
+  protected static final long serialVersionUID = 1L;
+
+  public ChiSquareDataSetEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
+    super(expression, factory);
+  }
+
+  @Override
+  public Object doWork(Object value1, Object value2) throws IOException {
+
+    List<Number> listA = (List<Number>) value1;
+    List<Number> listB = (List<Number>) value2;
+
+    long[] sampleA = new long[listA.size()];
+    long[] sampleB = new long[listB.size()];
+
+    for(int i=0; i<sampleA.length; i++) {
+      sampleA[i] = listA.get(i).longValue();
+    }
+
+    for(int i=0; i<sampleB.length; i++) {
+      sampleB[i] = listB.get(i).longValue();
+    }
+
+    ChiSquareTest chiSquareTest = new ChiSquareTest();
+    double chiSquare = chiSquareTest.chiSquareDataSetsComparison(sampleA, sampleB);
+    double p = chiSquareTest.chiSquareTestDataSetsComparison(sampleA, sampleB);
+
+    Map<String,Number> m = new HashMap<>();
+    m.put("chisquare-statistic", chiSquare);
+    m.put("p-value", p);
+    return new Tuple(m);
+
+  }
+}

solr/solrj/src/test/org/apache/solr/client/solrj/io/stream/StreamExpressionTest.java

@@ -7224,6 +7224,31 @@ public class StreamExpressionTest extends SolrCloudTestCase {
     assertEquals(pval3.doubleValue(), 0.0404907407662755, .0001);
   }
 
+
+  @Test
+  public void testChiSquareDataSet() throws Exception {
+    String cexpr = "let(echo=true," +
+                   "    a=array(1,1,2,3,4,5,6,7,9,10,11,12), " +
+                   "    b=array(1,1,2,3,4,5,6,7,1,1,1,1), " +
+                   "    chisquare=chiSquareDataSet(a, b))";
+
+    ModifiableSolrParams paramsLoc = new ModifiableSolrParams();
+    paramsLoc.set("expr", cexpr);
+    paramsLoc.set("qt", "/stream");
+    String url = cluster.getJettySolrRunners().get(0).getBaseUrl().toString()+"/"+COLLECTIONORALIAS;
+    TupleStream solrStream = new SolrStream(url, paramsLoc);
+    StreamContext context = new StreamContext();
+    solrStream.setStreamContext(context);
+    List<Tuple> tuples = getTuples(solrStream);
+    assertTrue(tuples.size() == 1);
+    Map testResult = (Map)tuples.get(0).get("chisquare");
+    Number tstat = (Number)testResult.get("chisquare-statistic");
+    Number pval = (Number)testResult.get("p-value");
+    assertEquals(tstat.doubleValue(), 20.219464814599252, .0001);
+    assertEquals(pval.doubleValue(), 0.04242018685334226, .0001);
+  }
+
+
   @Test
   public void testMultiVariateNormalDistribution() throws Exception {
     String cexpr = "let(echo=true," +