Add aggregator for calculating the population standard deviation

4 files changed, 81 insertions, 8 deletions

diff --git a/container-search/src/main/java/com/yahoo/search/grouping/request/StandardDeviationAggregator.java b/container-search/src/main/java/com/yahoo/search/grouping/request/StandardDeviationAggregator.java
new file mode 100644
index 00000000000..7211adbfe4d
--- /dev/null
+++ b/container-search/src/main/java/com/yahoo/search/grouping/request/StandardDeviationAggregator.java
@@ -0,0 +1,18 @@
+// Copyright 2017 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.grouping.request;
+
+/**
+ * This class represents an stddev-aggregator in a {@link GroupingExpression}. It evaluates to population standard deviation
+ * of the values that the contained expression evaluated to over all the inputs.
+ *
+ * @author bjorncs
+ */
+public class StandardDeviationAggregator extends AggregatorNode {
+
+    /**
+     * @param exp The expression to aggregate on.
+     */
+    public StandardDeviationAggregator(GroupingExpression exp) {
+        super("stddev", exp);
+    }
+}
diff --git a/container-search/src/main/java/com/yahoo/search/grouping/vespa/ExpressionConverter.java b/container-search/src/main/java/com/yahoo/search/grouping/vespa/ExpressionConverter.java
index 9de1c902be1..381724a08eb 100644
--- a/container-search/src/main/java/com/yahoo/search/grouping/vespa/ExpressionConverter.java
+++ b/container-search/src/main/java/com/yahoo/search/grouping/vespa/ExpressionConverter.java
@@ -68,6 +68,7 @@ import com.yahoo.search.grouping.request.ReverseFunction;
 import com.yahoo.search.grouping.request.SecondOfMinuteFunction;
 import com.yahoo.search.grouping.request.SizeFunction;
 import com.yahoo.search.grouping.request.SortFunction;
+import com.yahoo.search.grouping.request.StandardDeviationAggregator;
 import com.yahoo.search.grouping.request.StrCatFunction;
 import com.yahoo.search.grouping.request.StrLenFunction;
 import com.yahoo.search.grouping.request.StringValue;
@@ -86,7 +87,6 @@ import com.yahoo.search.grouping.request.YearFunction;
 import com.yahoo.search.grouping.request.YmumValue;
 import com.yahoo.search.grouping.request.ZCurveXFunction;
 import com.yahoo.search.grouping.request.ZCurveYFunction;
-
 import com.yahoo.searchlib.aggregation.AggregationResult;
 import com.yahoo.searchlib.aggregation.AverageAggregationResult;
 import com.yahoo.searchlib.aggregation.CountAggregationResult;
@@ -94,9 +94,9 @@ import com.yahoo.searchlib.aggregation.ExpressionCountAggregationResult;
 import com.yahoo.searchlib.aggregation.HitsAggregationResult;
 import com.yahoo.searchlib.aggregation.MaxAggregationResult;
 import com.yahoo.searchlib.aggregation.MinAggregationResult;
+import com.yahoo.searchlib.aggregation.StandardDeviationAggregationResult;
 import com.yahoo.searchlib.aggregation.SumAggregationResult;
 import com.yahoo.searchlib.aggregation.XorAggregationResult;
-
 import com.yahoo.searchlib.expression.AddFunctionNode;
 import com.yahoo.searchlib.expression.AggregationRefNode;
 import com.yahoo.searchlib.expression.AndFunctionNode;
@@ -235,6 +235,10 @@ class ExpressionConverter {
                     .setSummaryClass(summaryName != null ? summaryName : defaultSummaryName)
                     .setExpression(new ConstantNode(new IntegerResultNode(0)));
         }
+        if (exp instanceof StandardDeviationAggregator) {
+            return new StandardDeviationAggregationResult()
+                    .setExpression(toExpressionNode(((StandardDeviationAggregator) exp).getExpression()));
+        }
         if (exp instanceof XorAggregator) {
             return new XorAggregationResult()
                     .setExpression(toExpressionNode(((XorAggregator)exp).getExpression()));
diff --git a/container-search/src/main/java/com/yahoo/search/grouping/vespa/ResultBuilder.java b/container-search/src/main/java/com/yahoo/search/grouping/vespa/ResultBuilder.java
index 590b531812a..6caffc0d043 100644
--- a/container-search/src/main/java/com/yahoo/search/grouping/vespa/ResultBuilder.java
+++ b/container-search/src/main/java/com/yahoo/search/grouping/vespa/ResultBuilder.java
@@ -3,13 +3,50 @@ package com.yahoo.search.grouping.vespa;
 
 import com.yahoo.search.grouping.Continuation;
 import com.yahoo.search.grouping.GroupingRequest;
-import com.yahoo.search.grouping.result.*;
+import com.yahoo.search.grouping.result.DoubleBucketId;
+import com.yahoo.search.grouping.result.DoubleId;
 import com.yahoo.search.grouping.result.Group;
+import com.yahoo.search.grouping.result.GroupId;
+import com.yahoo.search.grouping.result.GroupList;
+import com.yahoo.search.grouping.result.HitList;
+import com.yahoo.search.grouping.result.LongBucketId;
+import com.yahoo.search.grouping.result.LongId;
+import com.yahoo.search.grouping.result.NullId;
+import com.yahoo.search.grouping.result.RawBucketId;
+import com.yahoo.search.grouping.result.RawId;
+import com.yahoo.search.grouping.result.RootGroup;
+import com.yahoo.search.grouping.result.StringBucketId;
+import com.yahoo.search.grouping.result.StringId;
 import com.yahoo.search.result.Relevance;
-import com.yahoo.searchlib.aggregation.*;
-import com.yahoo.searchlib.expression.*;
-
-import java.util.*;
+import com.yahoo.searchlib.aggregation.AggregationResult;
+import com.yahoo.searchlib.aggregation.AverageAggregationResult;
+import com.yahoo.searchlib.aggregation.CountAggregationResult;
+import com.yahoo.searchlib.aggregation.ExpressionCountAggregationResult;
+import com.yahoo.searchlib.aggregation.Grouping;
+import com.yahoo.searchlib.aggregation.Hit;
+import com.yahoo.searchlib.aggregation.HitsAggregationResult;
+import com.yahoo.searchlib.aggregation.MaxAggregationResult;
+import com.yahoo.searchlib.aggregation.MinAggregationResult;
+import com.yahoo.searchlib.aggregation.StandardDeviationAggregationResult;
+import com.yahoo.searchlib.aggregation.SumAggregationResult;
+import com.yahoo.searchlib.aggregation.XorAggregationResult;
+import com.yahoo.searchlib.expression.ExpressionNode;
+import com.yahoo.searchlib.expression.FloatBucketResultNode;
+import com.yahoo.searchlib.expression.FloatResultNode;
+import com.yahoo.searchlib.expression.IntegerBucketResultNode;
+import com.yahoo.searchlib.expression.IntegerResultNode;
+import com.yahoo.searchlib.expression.NullResultNode;
+import com.yahoo.searchlib.expression.RawBucketResultNode;
+import com.yahoo.searchlib.expression.RawResultNode;
+import com.yahoo.searchlib.expression.ResultNode;
+import com.yahoo.searchlib.expression.StringBucketResultNode;
+import com.yahoo.searchlib.expression.StringResultNode;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 
 /**
  * This class implements the necessary logic to build a {@link RootGroup} from a list of {@link Grouping} objects. It is
@@ -211,7 +248,9 @@ class ResultBuilder {
             } else if (execResult instanceof MinAggregationResult) {
                 return ((MinAggregationResult)execResult).getMin().getValue();
             } else if (execResult instanceof SumAggregationResult) {
-                return ((SumAggregationResult)execResult).getSum().getValue();
+                return ((SumAggregationResult) execResult).getSum().getValue();
+            } else if (execResult instanceof StandardDeviationAggregationResult) {
+                return ((StandardDeviationAggregationResult) execResult).getStandardDeviation();
             } else if (execResult instanceof XorAggregationResult) {
                 return ((XorAggregationResult)execResult).getXor();
             } else {
diff --git a/container-search/src/main/javacc/com/yahoo/search/grouping/request/parser/GroupingParser.jj b/container-search/src/main/javacc/com/yahoo/search/grouping/request/parser/GroupingParser.jj
index 89433ab52f5..e38195af374 100644
--- a/container-search/src/main/javacc/com/yahoo/search/grouping/request/parser/GroupingParser.jj
+++ b/container-search/src/main/javacc/com/yahoo/search/grouping/request/parser/GroupingParser.jj
@@ -139,6 +139,7 @@ TOKEN :
     <SORT: "sort"> |
     <INTERPOLATEDLOOKUP: "interpolatedlookup"> |
     <SQRT: "sqrt"> |
+    <STDDEV: "stddev"> |
     <STRCAT: "strcat"> |
     <STRLEN: "strlen"> |
     <SUB: "sub"> |
@@ -358,6 +359,7 @@ GroupingExpression value(GroupingOperation grp) :
                    exp = sortFunction(grp)             |
                    exp = arrayAtLookup(grp)            |
                    exp = interpolatedLookup(grp)       |
+                   exp = stddevAggregator(grp)         |
                    exp = stringValue()                 |
                    exp = strCatFunction(grp)           |
                    exp = strLenFunction(grp)           |
@@ -695,6 +697,15 @@ RawValue rawValue(GroupingOperation grp) :
     { return new RawValue(buffer); }
 }
 
+StandardDeviationAggregator stddevAggregator(GroupingOperation grp) :
+{
+    GroupingExpression exp;
+}
+{
+    ( <STDDEV> lbrace() exp = exp(grp) rbrace() )
+    { return new StandardDeviationAggregator(exp); }
+}
+
 StringValue stringValueUnquoted() :
 {
     String str;
@@ -1018,6 +1029,7 @@ String identifier() :
         <SORT> |
         <INTERPOLATEDLOOKUP> |
         <SQRT> |
+        <STDDEV> |
         <STRCAT> |
         <STRLEN> |
         <SUB> |