--- /dev/null
+/*
+ * Copyright (c) 2003-2005 The BISON Project
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program 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 program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+package peersim.util;
+
+import java.util.ArrayList;
+import java.util.Collections;
+
+/**
+ * This class adds the ability to retrieve the median element to the
+ * {@link IncrementalStats} class. Note that this class actually stores all
+ * the elements, so (unlike in its superclass) storage requirements depend
+ * on the number of items processed.
+ *
+ * @author giampa
+ */
+public class MedianStats extends IncrementalStats
+{
+
+/** Structure to store each entry. */
+private final ArrayList<Double> data=new ArrayList<Double>();
+
+/** Calls {@link #reset}. */
+public MedianStats()
+{
+ reset();
+}
+
+/**
+ * Retrieves the median in the current data collection.
+ *
+ * @return The current median value.
+ */
+public double getMedian()
+{
+ double result;
+
+ if (data.isEmpty())
+ throw new IllegalStateException("Data vector is empty!");
+
+ // Sort the arraylist
+ Collections.sort(data);
+ if (data.size() % 2 != 0) { // odd number
+ result = data.get(data.size() / 2);
+ } else { // even number:
+ double a = data.get(data.size() / 2);
+ double b = data.get(data.size() / 2 - 1);
+ result = (a + b) / 2;
+ }
+ return result;
+}
+
+public void add(double item, int k)
+{
+ for (int i = 0; i < k; ++i) {
+ super.add(item, 1);
+ data.add(new Double(item));
+ }
+}
+
+public void reset()
+{
+ super.reset();
+ if (data != null)
+ data.clear();
+}
+
+
+public static void main( String[] args ) {
+ MedianStats s = new MedianStats();
+ for(int i=0; i<args.length; i++) s.add(Double.parseDouble(args[i]));
+ System.out.println("Average: "+s.getAverage());
+ System.out.println("Median: "+s.getMedian());
+}
+
+}
