Scales the specified array of doubles so that they sum to one. - Java java.lang

Java examples for java.lang:Math Array Function

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Description

Scales the specified array of doubles so that they sum to one.

Demo Code

/**//w ww  .  java  2  s  .c o m
 * Java Modular Image Synthesis Toolkit (JMIST)
 * Copyright (C) 2008-2013 Bradley W. Kimmel
 *
 * 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.
 */
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

public class Main{
    /**
     * Scales the specified array of <code>double</code>s so that they sum to
     * one.
     * @param weights The array of <code>double</code>s to normalize (this
     *     array will be modified).
     * @return A reference to <code>weights</code>.
     */
    public static double[] normalize(double[] weights) {
        double sum = MathUtil.sum(weights);
        return MathUtil.scale(weights, 1.0 / sum);
    }
    /**
     * Computes the sum of the values in an array of <code>double</code>s.
     * @param array The array of <code>double</code>s of which to compute the
     *     sum.
     * @return The sum of the values in <code>array</code>.
     */
    public static double sum(double[] array) {
        double sum = 0.0;
        for (int i = 0; i < array.length; i++) {
            sum += array[i];
        }
        return sum;
    }
    /**
     * Computes the sum of the values in a collection of <code>double</code>s.
     * @param values The collection of <code>double</code>s of which to compute
     *     the  sum.
     * @return The sum of the values in <code>values</code>.
     */
    public static double sum(Iterable<Double> values) {
        double sum = 0.0;
        for (double x : values) {
            sum += x;
        }
        return sum;
    }
    /**
     * Computes the sum of the values in an array of <code>int</code>s.
     * @param array The array of <code>int</code>s of which to compute the sum.
     * @return The sum of the values in <code>array</code>.
     */
    public static int sum(int[] array) {
        int sum = 0;
        for (int i = 0; i < array.length; i++) {
            sum += array[i];
        }
        return sum;
    }
    /**
     * Multiplies all of the values in the specified array of
     * <code>double</code>s by the same value.
     * @param array The array of <code>double</code>s the elements of which are
     *     to be multiplied by a constant factor (the elements of this array
     *     will be modified).
     * @param factor The value by which to multiply each element of
     *     <code>array</code>.
     * @return A reference to <code>array</code>.
     */
    public static double[] scale(double[] array, double factor) {
        for (int i = 0; i < array.length; i++) {
            array[i] *= factor;
        }
        return array;
    }
    /**
     * Multiplies all of the values in the specified array of
     * <code>int</code>s by the same value.
     * @param array The array of <code>int</code>s the elements of which are
     *     to be multiplied by a constant factor (the elements of this array
     *     will be modified).
     * @param factor The value by which to multiply each element of
     *     <code>array</code>.
     * @return A reference to <code>array</code>.
     */
    public static int[] scale(int[] array, int factor) {
        for (int i = 0; i < array.length; i++) {
            array[i] *= factor;
        }
        return array;
    }
    /**
     * Multiplies all of the values in the specified array of
     * <code>long</code>s by the same value.
     * @param array The array of <code>long</code>s the elements of which are
     *     to be multiplied by a constant factor (the elements of this array
     *     will be modified).
     * @param factor The value by which to multiply each element of
     *     <code>array</code>.
     * @return A reference to <code>array</code>.
     */
    public static long[] scale(long[] array, long factor) {
        for (int i = 0; i < array.length; i++) {
            array[i] *= factor;
        }
        return array;
    }
}

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