Java List Variance variance(List data)

Description

Calculate variance of the array

License

Open Source License

Parameter

Parameter	Description
data	a parameter

Declaration

public static double variance(List<Double> data) 

Method Source Code

//package com.java2s;
/*//ww w  .j  a v a  2s. c om
* Open-Source tuning tools
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

import java.util.List;

public class Main {
    /**
     * Calculate variance of the array
     * @param data
     * @return
     */
    public static double variance(List<Double> data) {
        double mean = mean(data);
        double sum = 0;
        double diff = 0;
        for (Double d : data) {
            diff = d - mean;
            sum += (diff * diff);
        }
        return sum / data.size();
    }

    /**
     * Calculate mean of the array
     * @param data
     * @return
     */
    public static double mean(List<Double> data) {
        double val = 0;
        for (int i = 0; i < data.size(); ++i)
            val += data.get(i);
        return val / data.size();
    }
}

Related

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