SOLR-10582: Add Correlation Evaluator

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

@@ -236,6 +236,7 @@ public class StreamHandler extends RequestHandlerBase implements SolrCoreAware,
       .withFunctionName("cbrt", CubedRootEvaluator.class)
       .withFunctionName("coalesce", CoalesceEvaluator.class)
       .withFunctionName("uuid", UuidEvaluator.class)
+      .withFunctionName("corr", CorrelationEvaluator.class)
 
 
       // Conditional Stream Evaluators

solr/solrj/ivy.xml

@@ -33,6 +33,7 @@
     <dependency org="org.apache.httpcomponents" name="httpmime" rev="${/org.apache.httpcomponents/httpmime}" conf="compile"/>
     <dependency org="org.apache.httpcomponents" name="httpcore" rev="${/org.apache.httpcomponents/httpcore}" conf="compile"/>
     <dependency org="commons-io" name="commons-io" rev="${/commons-io/commons-io}" conf="compile"/>
+    <dependency org="org.apache.commons" name="commons-math3" rev="${/org.apache.commons/commons-math3}" conf="compile"/>
     <dependency org="org.codehaus.woodstox" name="woodstox-core-asl" rev="${/org.codehaus.woodstox/woodstox-core-asl}" conf="compile"/>
     <dependency org="org.codehaus.woodstox" name="stax2-api" rev="${/org.codehaus.woodstox/stax2-api}" conf="compile"/>
     <dependency org="org.noggit" name="noggit" rev="${/org.noggit/noggit}" conf="compile"/>

solr/solrj/src/java/org/apache/solr/client/solrj/io/stream/CorrelationEvaluator.java

@@ -0,0 +1,77 @@
+/*
+ * 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.stream;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.apache.commons.math3.stat.correlation.PearsonsCorrelation;
+import org.apache.solr.client.solrj.io.Tuple;
+import org.apache.solr.client.solrj.io.eval.ComplexEvaluator;
+import org.apache.solr.client.solrj.io.eval.StreamEvaluator;
+import org.apache.solr.client.solrj.io.stream.expr.Explanation;
+import org.apache.solr.client.solrj.io.stream.expr.Explanation.ExpressionType;
+import org.apache.solr.client.solrj.io.stream.expr.Expressible;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionParameter;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+
+public class CorrelationEvaluator extends ComplexEvaluator implements Expressible {
+
+  private static final long serialVersionUID = 1;
+
+  public CorrelationEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
+    super(expression, factory);
+  }
+
+  public Number evaluate(Tuple tuple) throws IOException {
+    StreamEvaluator colEval1 = subEvaluators.get(0);
+    StreamEvaluator colEval2 = subEvaluators.get(1);
+
+    List<Number> numbers1 = (List<Number>)colEval1.evaluate(tuple);
+    List<Number> numbers2 = (List<Number>)colEval2.evaluate(tuple);
+    double[] column1 = new double[numbers1.size()];
+    double[] column2 = new double[numbers2.size()];
+
+    for(int i=0; i<numbers1.size(); i++) {
+      column1[i] = numbers1.get(i).doubleValue();
+    }
+
+    for(int i=0; i<numbers2.size(); i++) {
+      column2[i] = numbers2.get(i).doubleValue();
+    }
+
+    PearsonsCorrelation pearsonsCorrelation = new PearsonsCorrelation();
+
+    return pearsonsCorrelation.correlation(column1, column2);
+  }
+
+  @Override
+  public StreamExpressionParameter toExpression(StreamFactory factory) throws IOException {
+    StreamExpression expression = new StreamExpression(factory.getFunctionName(getClass()));
+    return expression;
+  }
+
+  @Override
+  public Explanation toExplanation(StreamFactory factory) throws IOException {
+    return new Explanation(nodeId.toString())
+        .withExpressionType(ExpressionType.EVALUATOR)
+        .withFunctionName(factory.getFunctionName(getClass()))
+        .withImplementingClass(getClass().getName())
+        .withExpression(toExpression(factory).toString());
+  }
+}

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

@@ -5109,7 +5109,50 @@ public class StreamExpressionTest extends SolrCloudTestCase {
   }
 
 
+  @Test
+  public void testCorrelationStream() throws Exception {
+    UpdateRequest updateRequest = new UpdateRequest();
 
+    int i=0;
+    while(i<50) {
+      updateRequest.add(id, "id_"+(++i),"test_dt", getDateString("2016", "5", "1"), "price_f", "400.00");
+    }
+
+    while(i<100) {
+      updateRequest.add(id, "id_"+(++i),"test_dt", getDateString("2015", "5", "1"), "price_f", "300.0");
+    }
+
+    while(i<150) {
+      updateRequest.add(id, "id_"+(++i),"test_dt", getDateString("2014", "5", "1"), "price_f", "500.0");
+    }
+
+    while(i<250) {
+      updateRequest.add(id, "id_"+(++i),"test_dt", getDateString("2013", "5", "1"), "price_f", "100.00");
+    }
+
+    updateRequest.commit(cluster.getSolrClient(), COLLECTIONORALIAS);
+
+    String expr = "timeseries("+COLLECTIONORALIAS+", q=\"*:*\", start=\"2013-01-01T01:00:00.000Z\", " +
+        "end=\"2016-12-01T01:00:00.000Z\", " +
+        "gap=\"+1YEAR\", " +
+        "field=\"test_dt\", " +
+        "count(*), sum(price_f), max(price_f), min(price_f))";
+
+    String cexpr = "let(a="+expr+", b=select("+expr+",mult(-1, count(*)) as nvalue), c=col(a, count(*)), d=col(b, nvalue), tuple(corr=corr(c,d)))";
+
+    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);
+    assertTrue(tuples.get(0).getDouble("corr").equals(-1.0D));
+  }