Added a getUniqueCount() method to Frequency to return the number of unique

values included in the frequency table.

Reported and patched by Patrick Meyer
JIRA: MATH-414

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1044981 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/math/stat/Frequency.java

@@ -241,7 +241,15 @@ public class Frequency implements Serializable {
         return getCount(Character.valueOf(v));
     }
 
-    //-------------------------------------------------------------
+    /**
+     * Returns the number of values in the frequency table.
+     * 
+     * @return the number of unique values that have been added to the frequency table.
+     * @see #valuesIterator() 
+     */
+    public int getUniqueCount(){
+    	return freqTable.keySet().size();
+    }
 
     /**
      * Returns the percentage of values that are equal to v

src/site/xdoc/changes.xml

@@ -134,6 +134,10 @@ The <action> type attribute can be add,update,fix,remove.
       </action>
     </release>
     <release version="2.2" date="TBD" description="TBD">
+      <action dev="psteitz" type="update" issue="MATH-448" due-to="Patrick Meyer">
+        Added a getUniqueCount() method to Frequency to return the number of unique
+        values included in the frequency table.
+      </action>
       <action dev="psteitz" type="fix" issue="MATH-414">
         Modified NormalDistributionImpl.cumulativeProbability to return 0 or 1,
         respectively for values more than 40 standard deviations from the mean.

src/test/java/org/apache/commons/math/stat/FrequencyTest.java

@@ -251,5 +251,15 @@ public final class FrequencyTest extends TestCase {
         f.addValue(twoI);
         assertEquals(f, TestUtils.serializeAndRecover(f));
     }
+    
+    public void testGetUniqueCount() {
+        assertEquals(0, f.getUniqueCount());
+        f.addValue(oneL);
+        assertEquals(1, f.getUniqueCount());
+        f.addValue(oneL);
+        assertEquals(1, f.getUniqueCount());
+        f.addValue(twoI);
+        assertEquals(2, f.getUniqueCount());
+    }
 }