SOLR-11808: Add sumSq Stream Evaluator

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

@@ -287,6 +287,7 @@ public class StreamHandler extends RequestHandlerBase implements SolrCoreAware,
         .withFunctionName("integrate", IntegrateEvaluator.class)
         .withFunctionName("density", DensityEvaluator.class)
         .withFunctionName("mannWhitney", MannWhitneyUEvaluator.class)
+        .withFunctionName("sumSq", SumSqEvaluator.class)
 
         // Boolean Stream Evaluators
 

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

@@ -0,0 +1,56 @@
+/*
+ * 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.List;
+import java.util.Locale;
+
+import org.apache.commons.math3.stat.StatUtils;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+
+public class SumSqEvaluator extends RecursiveObjectEvaluator implements OneValueWorker {
+  private static final long serialVersionUID = 1;
+
+  public SumSqEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
+    super(expression, factory);
+  }
+
+  @Override
+  public Object doWork(Object value) throws IOException {
+    if(null == value){
+      return value;
+    }
+    else if(!(value instanceof List<?>)){
+      throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - found type %s for value, expecting a List",toExpression(constructingFactory), value.getClass().getSimpleName()));
+    }
+
+    List<Number> list = (List<Number>)value;
+
+    if(0 == list.size()){
+      return list;
+    }
+
+    double[] vec = new double[list.size()];
+    for(int i=0; i< vec.length; i++) {
+      vec[i] = list.get(i).doubleValue();
+    }
+
+    return StatUtils.sumSq(vec);
+  }
+}

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

@@ -7549,6 +7549,23 @@ public class StreamExpressionTest extends SolrCloudTestCase {
     assertEquals(out.get(2).doubleValue(), 10.0, .0);
   }
 
+  @Test
+  public void testSumSq() throws Exception {
+    String cexpr = "sumSq(array(-3,-2.5, 10))";
+    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);
+    Number sumSq = (Number)tuples.get(0).get("return-value");
+    assertEquals(sumSq.doubleValue(), 115.25D, 0.0D);
+  }
+
+
   @Test
   public void testMonteCarlo() throws Exception {
     String cexpr = "let(a=constantDistribution(10), b=constantDistribution(20), c=monteCarlo(add(sample(a), sample(b)), 10))";