Java Array Normalize normalizeFromLog10(double[] array)

Description

normalizes the log10-based array.

License

Open Source License

Parameter

Parameter	Description
array	the array to be normalized

Return

a newly allocated array corresponding the normalized values in array

Declaration

public static double[] normalizeFromLog10(double[] array) 

Method Source Code

//package com.java2s;
/*/*from   w  ww .j  a  va 2  s.  c  o m*/
* Copyright (c) 2012 The Broad Institute
* 
* 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.
*/

public class Main {
    /**
     * The smallest log10 value we'll emit from normalizeFromLog10 and other functions
     * where the real-space value is 0.0.
     */
    public final static double LOG10_P_OF_ZERO = -1000000.0;

    /**
     * normalizes the log10-based array.  ASSUMES THAT ALL ARRAY ENTRIES ARE <= 0 (<= 1 IN REAL-SPACE).
     *
     * @param array the array to be normalized
     * @return a newly allocated array corresponding the normalized values in array
     */
    public static double[] normalizeFromLog10(double[] array) {
        return normalizeFromLog10(array, false);
    }

    /**
     * normalizes the log10-based array.  ASSUMES THAT ALL ARRAY ENTRIES ARE <= 0 (<= 1 IN REAL-SPACE).
     *
     * @param array             the array to be normalized
     * @param takeLog10OfOutput if true, the output will be transformed back into log10 units
     * @return a newly allocated array corresponding the normalized values in array, maybe log10 transformed
     */
    public static double[] normalizeFromLog10(double[] array, boolean takeLog10OfOutput) {
        return normalizeFromLog10(array, takeLog10OfOutput, false);
    }

    /**
     * See #normalizeFromLog10 but with the additional option to use an approximation that keeps the calculation always in log-space
     *
     * @param array
     * @param takeLog10OfOutput
     * @param keepInLogSpace
     *
     * @return
     */
    public static double[] normalizeFromLog10(double[] array, boolean takeLog10OfOutput, boolean keepInLogSpace) {
        // for precision purposes, we need to add (or really subtract, since they're
        // all negative) the largest value; also, we need to convert to normal-space.
        double maxValue = arrayMax(array);

        // we may decide to just normalize in log space without converting to linear space
        if (keepInLogSpace) {
            for (int i = 0; i < array.length; i++) {
                array[i] -= maxValue;
            }
            return array;
        }

        // default case: go to linear space
        double[] normalized = new double[array.length];

        for (int i = 0; i < array.length; i++)
            normalized[i] = Math.pow(10, array[i] - maxValue);

        // normalize
        double sum = 0.0;
        for (int i = 0; i < array.length; i++)
            sum += normalized[i];
        for (int i = 0; i < array.length; i++) {
            double x = normalized[i] / sum;
            if (takeLog10OfOutput) {
                x = Math.log10(x);
                if (x < LOG10_P_OF_ZERO || Double.isInfinite(x))
                    x = array[i] - maxValue;
            }

            normalized[i] = x;
        }

        return normalized;
    }

    public static double arrayMax(final double[] array) {
        return array[maxElementIndex(array, array.length)];
    }

    public static int maxElementIndex(final double[] array) {
        return maxElementIndex(array, array.length);
    }

    public static int maxElementIndex(final double[] array, final int endIndex) {
        if (array == null || array.length == 0)
            throw new IllegalArgumentException("Array cannot be null!");

        int maxI = 0;
        for (int i = 1; i < endIndex; i++) {
            if (array[i] > array[maxI])
                maxI = i;
        }

        return maxI;
    }
}

Related

1. normalizeCoordsSum(float[] vector, float newSum)
2. normalizedBySum(double[] values)
3. normalizedTermMu(double ui, double[] uis)
4. normalizeFloatArray(float[] buffer, float peak, float target)
5. normalizeForce(double[] data)
6. normalizeFromLog10(double[] array, boolean takeLog10OfOutput)
7. normalizeFromLog10(final double[] array, final boolean takeLog10OfOutput, final boolean keepInLogSpace)
8. normalizeFromRealSpace(final double[] array)
9. normalizeHeightMap(float heightMap[])