Added getSumOfLogs method to SummaryStatistics and made

sum of logs instance used by GeometricMean configurable.
JIRA: MATH-191


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@620221 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/math/stat/descriptive/SummaryStatistics.java

@@ -120,7 +120,7 @@ public class SummaryStatistics implements StatisticalSummary, Serializable {
     protected SumOfLogs sumLog = new SumOfLogs();
 
     /** geoMean of values that have been added */
-    protected GeometricMean geoMean = new GeometricMean();
+    protected GeometricMean geoMean = new GeometricMean(sumLog);
 
     /** mean of values that have been added */
     protected Mean mean = new Mean();
@@ -174,16 +174,18 @@ public class SummaryStatistics implements StatisticalSummary, Serializable {
         minImpl.increment(value);
         maxImpl.increment(value);
         sumLogImpl.increment(value);
-        geoMean.increment(value);
         secondMoment.increment(value);
-        // If mean or variance have been overridden,
+        // If mean, variance or geomean have been overridden,
-        // need to increment these, since they don't have secondMoment
+        // need to increment these
         if (!(meanImpl instanceof Mean)) {
                 meanImpl.increment(value);
         }
         if (!(varianceImpl instanceof Variance)) {
             varianceImpl.increment(value);
         }
+        if (!(geoMeanImpl instanceof GeometricMean)) {
+            geoMeanImpl.increment(value);
+        }
         n++;
     }
 
@@ -296,6 +298,17 @@ public class SummaryStatistics implements StatisticalSummary, Serializable {
         return geoMeanImpl.getResult();
     }
     
+    /**
+     * Returns the sum of the logs of the values that have been added.
+     * <p>
+     *  Double.NaN is returned if no values have been added.</p>
+     *
+     * @return the sum of logs  
+     */
+    public double getSumOfLogs() {
+        return sumLogImpl.getResult();
+    }
+    
     /**
      * Generates a text report displaying
      * summary statistics from values that
@@ -313,6 +326,7 @@ public class SummaryStatistics implements StatisticalSummary, Serializable {
         outBuffer.append("variance: " + getVariance() + "\n");
         outBuffer.append("sum of squares: " + getSumsq() + "\n");
         outBuffer.append("standard deviation: " + getStandardDeviation() + "\n");
+        outBuffer.append("sum of logs: " + getSumOfLogs() + "\n");
         return outBuffer.toString();
     }
 
@@ -505,6 +519,7 @@ public class SummaryStatistics implements StatisticalSummary, Serializable {
             StorelessUnivariateStatistic sumLogImpl) {
         checkEmpty();
         this.sumLogImpl = sumLogImpl;
+        geoMean.setSumLogImpl(sumLogImpl);
     }
 
     /**

src/java/org/apache/commons/math/stat/descriptive/moment/GeometricMean.java

@@ -17,6 +17,7 @@
 package org.apache.commons.math.stat.descriptive.moment;
 
 import org.apache.commons.math.stat.descriptive.AbstractStorelessUnivariateStatistic;
+import org.apache.commons.math.stat.descriptive.StorelessUnivariateStatistic;
 import org.apache.commons.math.stat.descriptive.summary.SumOfLogs;
 
 /**
@@ -49,7 +50,7 @@ public class GeometricMean extends AbstractStorelessUnivariateStatistic {
     private static final long serialVersionUID = -8178734905303459453L;  
     
     /** Wrapped SumOfLogs instance */
-    private SumOfLogs sumOfLogs;
+    private StorelessUnivariateStatistic sumOfLogs;
 
     /**
      * Create a GeometricMean instance
@@ -58,6 +59,13 @@ public class GeometricMean extends AbstractStorelessUnivariateStatistic {
         sumOfLogs = new SumOfLogs();
     }
     
+    /**
+     * Create a GeometricMean instance using the given SumOfLogs instance
+     */
+    public GeometricMean(SumOfLogs sumOfLogs) {
+        this.sumOfLogs = sumOfLogs;
+    }
+    
     /**
      * @see org.apache.commons.math.stat.descriptive.StorelessUnivariateStatistic#increment(double)
      */
@@ -111,5 +119,41 @@ public class GeometricMean extends AbstractStorelessUnivariateStatistic {
     public long getN() {
         return sumOfLogs.getN();
     }
+    
+    /**
+     * <p>Sets the implementation for the sum of logs.</p>
+     * <p>This method must be activated before any data has been added - i.e.,
+     * before {@link #addValue(double) addValue} has been used to add data; 
+     * otherwise an IllegalStateException will be thrown.</p>
+     * 
+     * @param sumLogImpl the StorelessUnivariateStatistic instance to use
+     * for computing the log sum
+     * @throws IllegalStateException if data has already been added 
+     *  (i.e if n > 0)
+     */
+    public void setSumLogImpl(
+            StorelessUnivariateStatistic sumLogImpl) {
+        checkEmpty();
+        this.sumOfLogs = sumLogImpl;
+    }
+    
+    /**
+     * Returns the currently configured sum of logs implementation
+     * 
+     * @return the StorelessUnivariateStatistic implementing the log sum
+     */
+    public StorelessUnivariateStatistic getSumLogImpl() {
+        return sumOfLogs;
+    }
+    
+    /**
+     * Throws IllegalStateException if n > 0.
+     */
+    private void checkEmpty() {
+        if (getN() > 0) {
+            throw new IllegalStateException(
+                "Implementation must be configured before values are added.");
+        }
+    }
 
 }

src/site/xdoc/changes.xml

@@ -162,7 +162,11 @@ Commons Math Release Notes</title>
         covariance)
       </action>
       <action dev="luc" type="add" >
-        Added multivariate summary statistics
+        Added multivariate summary statistics.
+      </action>
+      <action dev="psteitz" type="update" issue="MATH-191">
+        Added getSumOfLogs method to SummaryStatistics and made SumOfLogs
+        instance used by GeometricMean configurable.
       </action>
     </release>
     <release version="1.1" date="2005-12-17"  

src/test/org/apache/commons/math/stat/descriptive/SummaryStatisticsTest.java

@@ -21,6 +21,7 @@ import junit.framework.Test;
 import junit.framework.TestSuite;
 
 import org.apache.commons.math.stat.descriptive.moment.Mean;
+import org.apache.commons.math.stat.descriptive.summary.Sum;
 /**
  * Test cases for the {@link SummaryStatistics} class.
  * When SummaryStatisticsImpl is removed in math 2.0, test cases from
@@ -47,10 +48,13 @@ public final class SummaryStatisticsTest extends SummaryStatisticsAbstractTest {
     
     public void testSetterInjection() throws Exception {
         SummaryStatistics u = createSummaryStatistics();
-        u.setMeanImpl(new sumMean());
+        u.setMeanImpl(new Sum());
+        u.setSumLogImpl(new Sum());
         u.addValue(1);
         u.addValue(3);
         assertEquals(4, u.getMean(), 1E-14);
+        assertEquals(4, u.getSumOfLogs(), 1E-14);
+        assertEquals(Math.exp(2), u.getGeometricMean(), 1E-14);
         u.clear();
         u.addValue(1);
         u.addValue(2);
@@ -64,44 +68,10 @@ public final class SummaryStatisticsTest extends SummaryStatisticsAbstractTest {
         u.addValue(1);
         u.addValue(3);
         try {
-            u.setMeanImpl(new sumMean());
+            u.setMeanImpl(new Sum());
             fail("Expecting IllegalStateException");
         } catch (IllegalStateException ex) {
             // expected
         }
     }
-    
-    /**
-     * Bogus mean implementation to test setter injection.
-     * Returns the sum instead of the mean.
-     */
-    static class sumMean implements StorelessUnivariateStatistic {   
-        private static final long serialVersionUID = 6492471391340853423L;
-        private double sum = 0;
-        private long n = 0;
-        public double evaluate(double[] values, int begin, int length) {
-            return 0;
-        }
-        public double evaluate(double[] values) {
-            return 0;
-        }
-        public void clear() {
-          sum = 0; 
-          n = 0;
-        }
-        public long getN() {
-            return n;
-        }
-        public double getResult() {
-            return sum;
-        }
-        public void increment(double d) {
-            sum += d;
-            n++;
-        }
-        public void incrementAll(double[] values, int start, int length) {
-        }
-        public void incrementAll(double[] values) {
-        }   
-    }  
 }