SOLR-10696: Add empirical distribution and percentile Stream Evaluators

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

@@ -179,6 +179,8 @@ public class StreamHandler extends RequestHandlerBase implements SolrCoreAware,
       .withFunctionName("scale", ScaleEvaluator.class)
       .withFunctionName("distance", DistanceEvaluator.class)
       .withFunctionName("copyOf", CopyOfEvaluator.class)
+      .withFunctionName("percentile", PercentileEvaluator.class)
+      .withFunctionName("empiricalDistribution", EmpiricalDistributionEvaluator.class)
 
       // metrics
          .withFunctionName("min", MinMetric.class)

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

@@ -0,0 +1,129 @@
+/*
+ * 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.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Arrays;
+
+import org.apache.commons.math3.random.EmpiricalDistribution;
+import org.apache.commons.math3.stat.descriptive.StatisticalSummary;
+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 EmpiricalDistributionEvaluator extends ComplexEvaluator implements Expressible {
+
+  private static final long serialVersionUID = 1;
+
+  public EmpiricalDistributionEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
+    super(expression, factory);
+  }
+
+  public Tuple evaluate(Tuple tuple) throws IOException {
+
+    if(subEvaluators.size() != 1) {
+      throw new IOException("Empirical dist expects 1 column as a parameters");
+    }
+
+    StreamEvaluator colEval1 = subEvaluators.get(0);
+
+    List<Number> numbers1 = (List<Number>)colEval1.evaluate(tuple);
+    double[] column1 = new double[numbers1.size()];
+
+    for(int i=0; i<numbers1.size(); i++) {
+      column1[i] = numbers1.get(i).doubleValue();
+    }
+
+    Arrays.sort(column1);
+    EmpiricalDistribution empiricalDistribution = new EmpiricalDistribution();
+    empiricalDistribution.load(column1);
+
+    Map map = new HashMap();
+    StatisticalSummary statisticalSummary = empiricalDistribution.getSampleStats();
+
+    map.put("max", statisticalSummary.getMax());
+    map.put("mean", statisticalSummary.getMean());
+    map.put("min", statisticalSummary.getMin());
+    map.put("stdev", statisticalSummary.getStandardDeviation());
+    map.put("sum", statisticalSummary.getSum());
+    map.put("N", statisticalSummary.getN());
+    map.put("var", statisticalSummary.getVariance());
+
+    return new EmpiricalDistributionTuple(empiricalDistribution, column1, map);
+  }
+
+  public static class EmpiricalDistributionTuple extends Tuple {
+
+    private EmpiricalDistribution empiricalDistribution;
+    private double[] backingArray;
+
+    public EmpiricalDistributionTuple(EmpiricalDistribution empiricalDistribution, double[] backingArray, Map map) {
+      super(map);
+      this.empiricalDistribution = empiricalDistribution;
+      this.backingArray = backingArray;
+    }
+
+    public double percentile(double d) {
+      int slot = Arrays.binarySearch(backingArray, d);
+
+      if(slot == 0) {
+        return 0.0;
+      }
+
+      if(slot < 0) {
+        if(slot == -1) {
+          return 0.0D;
+        } else {
+          //Not a direct hit
+          slot = Math.abs(slot);
+          --slot;
+          if(slot == backingArray.length) {
+            return 1.0D;
+          } else {
+            return (this.empiricalDistribution.cumulativeProbability(backingArray[slot]));
+          }
+        }
+      } else {
+        return this.empiricalDistribution.cumulativeProbability(backingArray[slot]);
+      }
+    }
+  }
+
+  @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/java/org/apache/solr/client/solrj/io/stream/PercentileEvaluator.java

@@ -0,0 +1,68 @@
+/*
+ * 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 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 PercentileEvaluator extends ComplexEvaluator implements Expressible {
+
+  private static final long serialVersionUID = 1;
+
+  public PercentileEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
+    super(expression, factory);
+  }
+
+  public Number evaluate(Tuple tuple) throws IOException {
+
+    if(subEvaluators.size() != 2) {
+      throw new IOException("Percentile expects 2 parameters: a regression result and a number");
+    }
+
+    StreamEvaluator r = subEvaluators.get(0);
+    StreamEvaluator d = subEvaluators.get(1);
+
+    EmpiricalDistributionEvaluator.EmpiricalDistributionTuple e = (EmpiricalDistributionEvaluator.EmpiricalDistributionTuple)r.evaluate(tuple);
+    Number n = (Number)d.evaluate(tuple);
+    return e.percentile(n.doubleValue());
+  }
+
+  @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

@@ -5467,6 +5467,53 @@ public class StreamExpressionTest extends SolrCloudTestCase {
     assertTrue(copy3.get(1).doubleValue() == 500D);
   }
 
+
+  @Test
+  public void testPercentiles() throws Exception {
+    UpdateRequest updateRequest = new UpdateRequest();
+
+    int i=0;
+    while(i<100) {
+      i=i+2;
+      updateRequest.add(id, "id_"+(i), "price_f", Integer.toString(i));
+    }
+
+    updateRequest.commit(cluster.getSolrClient(), COLLECTIONORALIAS);
+
+    String expr = "search("+COLLECTIONORALIAS+", q=\"*:*\", fl=\"price_f\", sort=\"price_f asc\", rows=\"200\")";
+    String cexpr = "let(a="+expr+", c=col(a, price_f), e=empiricalDistribution(c), " +
+        "tuple(p1=percentile(e, 88), " +
+        "p2=percentile(e, 2), " +
+        "p3=percentile(e, 99), " +
+        "p4=percentile(e, 77), " +
+        "p5=percentile(e, 98)))";
+
+    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);
+    double percentile1 = tuples.get(0).getDouble("p1");
+    double percentile2 = tuples.get(0).getDouble("p2");
+    double percentile3 = tuples.get(0).getDouble("p3");
+    double percentile4 = tuples.get(0).getDouble("p4");
+    double percentile5 = tuples.get(0).getDouble("p5");
+
+
+    assertEquals(.88D, percentile1, 0.001);
+    assertEquals(.0D, percentile2, 0.001);
+    assertEquals(1.0D, percentile3, 0.001);
+    assertEquals(.78D, percentile4, 0.001);
+    assertEquals(.98D, percentile5, 0.001);
+
+  }
+
   @Test
   public void testRankTransform() throws Exception {
     UpdateRequest updateRequest = new UpdateRequest();