/*
* $Id$
*
* Copyright 2006, The jCoderZ.org Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
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* its contributors may be used to endorse or promote products
* derived from this software without specific prior written
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*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS
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*/
package org.jcoderz.commons.statistics;
/**
* Compute the average of a number of positive long values.
* @author Albrecht Messner
*/
public class Average
implements Resettable
{
private final String mName;
private long mNumberOfValues;
private long mMinimumValue;
private long mMaximumValue;
private long mSumOfValues;
/**
* Constructor.
* @param name The name of the average
*/
public Average (String name)
{
mName = name;
mNumberOfValues = 0;
mMinimumValue = Long.MAX_VALUE;
mMaximumValue = 0;
mSumOfValues = 0;
}
/** {@inheritDoc} */
public synchronized void reset ()
{
mNumberOfValues = 0;
mMinimumValue = Long.MAX_VALUE;
mMaximumValue = 0;
mSumOfValues = 0;
}
/**
* Update the average value with the given argument.
* @param value the value with which the average is updated
*/
public void update (long value)
{
if (value < 0)
{
throw new IllegalArgumentException("Values < 0 not allowed");
}
long lastSumOfValues;
long sumOfValues;
synchronized (this)
{
if (value < mMinimumValue)
{
mMinimumValue = value;
}
if (value > mMaximumValue)
{
mMaximumValue = value;
}
lastSumOfValues = mSumOfValues;
mSumOfValues += value;
sumOfValues = mSumOfValues;
mNumberOfValues++;
}
if (sumOfValues < lastSumOfValues)
{
throw new RuntimeException("Sum overflow: "
+ lastSumOfValues + " + " + value + " gives " + sumOfValues);
}
}
/**
* Computes the average of the values added with {@link #update(long)}
* so far.
* @return the average
*/
public synchronized long getAverage ()
{
final long avg;
if (mNumberOfValues > 0)
{
avg = mSumOfValues / mNumberOfValues;
}
else
{
avg = 0;
}
return avg;
}
/**
* Returns the minimum value of this average, or Long.MAX_VALUE if
* no value has been added so far.
* @return the minimum value of this average
*/
public synchronized long getMinimum ()
{
return mMinimumValue;
}
/**
* Returns the maximum value of this average, or zero if no
* value has been added so far.
* @return the maximum value of this average
*/
public synchronized long getMaximum ()
{
return mMaximumValue;
}
/**
* Returns the number of values that have been added to this average.
* @return the number of values that have been added to this average
*/
public synchronized long getCount ()
{
return mNumberOfValues;
}
/** {@inheritDoc} */
public String toString ()
{
final StringBuffer sbuf = new StringBuffer();
sbuf.append("[Average ").append(mName);
sbuf.append(" count=").append(getCount());
sbuf.append(", min=").append(getMinimum());
sbuf.append(", avg=").append(getAverage());
sbuf.append(", max=").append(getMaximum());
sbuf.append(']');
return sbuf.toString();
}
/**
* Returns the name.
* @return String
*/
public String getName ()
{
return mName;
}
}