Java List Variance variance(final List list)

Description

Variance.

License

GNU General Public License

Parameter

Parameter	Description
list	the list

Return

the double

Declaration

public static double variance(final List<Double> list) 

Method Source Code

//package com.java2s;
/*/* w  ww  .  ja  v a2s. c  om*/
 * Title:        CloudSim Toolkit
 * Description:  CloudSim (Cloud Simulation) Toolkit for Modeling and Simulation of Clouds
 * Licence:      GPL - http://www.gnu.org/copyleft/gpl.html
 *
 * Copyright (c) 2009-2012, The University of Melbourne, Australia
 */

import java.util.List;

public class Main {
    /**
     * Variance.
     * 
     * @param list the list
     * @return the double
     */
    public static double variance(final List<Double> list) {
        long n = 0;
        double mean = mean(list);
        double s = 0.0;

        for (double x : list) {
            n++;
            double delta = x - mean;
            mean += delta / n;
            s += delta * (x - mean);
        }
        // if you want to calculate std deviation
        // of a sample change this to (s/(n-1))
        return s / (n - 1);
    }

    /**
     * Gets the average.
     * 
     * @param list the list
     * 
     * @return the average
     */
    public static double mean(final List<Double> list) {
        double sum = 0;
        for (Double number : list) {
            sum += number;
        }
        return sum / list.size();
    }
}

Related

1. variance(ArrayList doubleArrayList)
2. variance(List data)
3. variance(List observations)
4. variance(List values)
5. variance(List data)