Java Matrix Sum sumAxis1(double[][] X)

Description

sum Axis

License

Open Source License

Declaration

static double[] sumAxis1(double[][] X) 

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.//w ww.  j  a v a 2s .co m
 *******************************************************************************/

public class Main {
    static double[] sumAxis1(double[][] X) {
        int n = X.length;
        double[] array = new double[n];
        for (int i = 0; i < n; i++) {
            double[] x = row(X, i);
            array[i] = sum(x);
        }
        return array;
    }

    public static double[] row(double[][] array, int i) {
        return array[i];
    }

    public static double sum(double[] x) {
        int n = x.length;
        double s = 0;
        for (int i = 0; i < n; i++) {
            s += x[i];
        }
        return s;
    }

    public static double[] sum(double[][] X, int axis) {
        if (axis == 0) {
            return sumAxis0(X);
        } else if (axis == 1) {
            return sumAxis1(X);
        } else {
            String message = "axis>=2 is not supported in sum method.";
            throw new RuntimeException(message);
        }
    }

    static double[] sumAxis0(double[][] X) {
        int m = X[0].length;
        double[] array = new double[m];
        for (int j = 0; j < m; j++) {
            double[] x = column(X, j);
            array[j] = sum(x);
        }
        return array;
    }

    public static double[] column(double[][] array, int j) {
        int rows = array.length;
        double[] colvec = new double[rows];
        for (int i = 0; i < rows; i++) {
            colvec[i] = array[i][j];
        }
        return colvec;
    }
}

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