Implemented a simple histogram tracking class.

git-svn-id: https://samskivert.googlecode.com/svn/trunk@579 6335cc39-0255-0410-8fd6-9bcaacd3b74c

projects/samskivert/src/java/com/samskivert/util/Histogram.java

@@ -0,0 +1,99 @@
+//
+// $Id: Histogram.java,v 1.1 2002/02/18 06:22:56 mdb Exp $
+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2001 Michael Bayne
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.util;
+
+import java.util.Arrays;
+
+/**
+ * Used for tracking a set of values that fall into a discrete range of
+ * values.
+ */
+public class Histogram
+{
+    /**
+     * Constructs a histogram that will track values with a granularity
+     * equal to the <code>bucketWidth</code> from <code>minValue</code> to
+     * <code>minValue + bucketWidth*bucketCount</code>.
+     */
+    public Histogram (int minValue, int bucketWidth, int bucketCount)
+    {
+        _minValue = minValue;
+        _maxValue = minValue + bucketWidth*bucketCount;
+        _bucketWidth = bucketWidth;
+        _buckets = new int[bucketCount];
+    }
+
+    /**
+     * Registers a value with this histogram.
+     */
+    public void addValue (int value)
+    {
+        if (value < _minValue) {
+            _buckets[0]++;
+        } else if (value >= _maxValue) {
+            _buckets[_buckets.length-1]++;
+        } else {
+            _buckets[(value-_minValue)/_bucketWidth]++;
+        }
+    }
+
+    /**
+     * Clears the values from this histogram.
+     */
+    public void clear ()
+    {
+        Arrays.fill(_buckets, 0);
+    }
+
+    /**
+     * Returns the array containing the bucket values. The zeroth element
+     * contains the count of all values less than <code>minValue</code>,
+     * the subsequent <code>bucketCount</code> elements contain the count
+     * of values falling into those buckets and the last element contains
+     * values greater than or equal to <code>maxValue</code>.
+     */
+    public int[] getBuckets ()
+    {
+        return _buckets;
+    }
+
+    /**
+     * Returns a string representation of this histogram.
+     */
+    public String toString ()
+    {
+        return "[min=" + _minValue + ", max=" + _maxValue +
+            ", bwidth=" + _bucketWidth +
+            ", buckets=" + StringUtil.toString(_buckets) + "]";
+    }
+
+    /** The minimum value tracked by this histogram. */
+    protected int _minValue;
+
+    /** The maximum value tracked by this histogram. */
+    protected int _maxValue;
+
+    /** The size of each histogram bucket. */
+    protected int _bucketWidth;
+
+    /** The histogram buckets. */
+    protected int[] _buckets;
+}