Java stddev stdev(double[] array)

Description

stdev

License

Open Source License

Declaration

public static double stdev(double[] array) 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * Copyright (c) 2014, 2015 IBM Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.//from w  ww  .j  a  va  2s  .  co m
 *******************************************************************************/

public class Main {
    public static double stdev(double[] array) {
        double var = var(array);
        return Math.sqrt(var);
    }

    public static double[] stdev(double[][] array) {
        double[] var = var(array);
        for (int i = 0; i < var.length; i++) {
            var[i] = Math.sqrt(var[i]);
        }
        return var;
    }

    public static double var(double[] array) {
        double mean = mean(array);
        int n = array.length;
        double var = 0;
        for (int i = 0; i < n; i++) {
            double val = array[i] - mean;
            var += val * val;
        }
        return var / n;
    }

    public static double[] var(double[][] array) {
        double[] mean = mean(array);

        int n = array.length;
        int m = array[0].length;

        double[] var = new double[m];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                double val = array[i][j] - mean[j];
                var[j] += val * val;
            }
        }
        for (int j = 0; j < m; j++) {
            var[j] /= n;
        }
        return var;
    }

    public static float mean(float[] array) {
        return (float) mean(toDouble(array));
    }

    public static double mean(double[] array) {
        int n = array.length;
        double sum = 0;

        for (int i = 0; i < n; i++) {
            sum += array[i];
        }
        double mean = sum / ((double) n);
        return mean;
    }

    public static double[] mean(double[][] array) {
        int n = array.length;
        int m = array[0].length;

        double[] mean = new double[m];

        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                mean[j] += array[i][j];
            }
        }
        for (int j = 0; j < m; j++) {
            mean[j] /= n;
        }
        return mean;
    }

    public static double[] toDouble(float[] array) {
        int n = array.length;
        double[] a2 = new double[n];
        for (int i = 0; i < n; i++) {
            a2[i] = array[i];
        }
        return a2;
    }
}

Related

1. stdDev(T[] array)
2. stdDeviation(int[] data)
3. stdev(Collection values)
4. stdev(Collection values)
5. stdev(double... array)
6. stdev(final double... values)
7. stdev(long[] vals, long average)