Java Array Convert to toDoubleArray(byte[] data)

Description

Convenience method for creating a double array from a byte array.

License

Open Source License

Parameter

Parameter	Description
data	a parameter

Declaration

public static double[] toDoubleArray(byte[] data)

Method Source Code

//package com.java2s;
/*/*from w ww  . j  a v a 2s  . c  o m*/
 * This file is part of the LIRE project: http://www.semanticmetadata.net/lire
 * LIRE 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.
 *
 * LIRE 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 LIRE; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * We kindly ask you to refer the any or one of the following publications in
 * any publication mentioning or employing Lire:
 *
 * Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval ?
 * An Extensible Java CBIR Library. In proceedings of the 16th ACM International
 * Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008
 * URL: http://doi.acm.org/10.1145/1459359.1459577
 *
 * Lux Mathias. Content Based Image Retrieval with LIRE. In proceedings of the
 * 19th ACM International Conference on Multimedia, pp. 735-738, Scottsdale,
 * Arizona, USA, 2011
 * URL: http://dl.acm.org/citation.cfm?id=2072432
 *
 * Mathias Lux, Oge Marques. Visual Information Retrieval using Java and LIRE
 * Morgan & Claypool, 2013
 * URL: http://www.morganclaypool.com/doi/abs/10.2200/S00468ED1V01Y201301ICR025
 *
 * Copyright statement:
 * ====================
 * (c) 2002-2013 by Mathias Lux (mathias@juggle.at)
 *  http://www.semanticmetadata.net/lire, http://www.lire-project.net
 *
 * Updated: 26.04.13 09:03
 */

import java.util.*;

public class Main {
    /**
     * Convenience method for creating a double array from a byte array.
     *
     * @param data
     * @return
     */
    public static double[] toDoubleArray(byte[] data) {
        double[] result = new double[data.length / 8];
        byte[] tmp = new byte[8];
        for (int i = 0; i < result.length; i++) {
            System.arraycopy(data, i * 8, tmp, 0, 8);
            result[i] = toDouble(tmp);
        }
        return result;
    }

    /**
     * Convenience method for creating a double array from a byte array.
     *
     * @param data
     * @param length
     * @param offset
     * @return
     */
    public static double[] toDoubleArray(byte[] data, int offset, int length) {
        double[] result = new double[length / 8];
        byte[] tmp = new byte[8];
        for (int i = 0; i < result.length; i++) {
            System.arraycopy(data, i * 8 + offset, tmp, 0, 8);
            result[i] = toDouble(tmp);
        }
        return result;
    }

    public static double[] toDoubleArray(float[] d) {
        double[] result = new double[d.length];
        for (int i = 0; i < result.length; i++) {
            result[i] = (double) d[i];
        }
        return result;
    }

    /**
     * Create a double[] from an int[]<br/>
     * by patch contributed by Franz Graf, franz.graf@gmail.com
     *
     * @param ints the int array
     * @return a new array of doubles
     */
    public static double[] toDoubleArray(int[] ints) {
        double[] result = new double[ints.length];
        for (int i = 0; i < result.length; i++) {
            result[i] = (double) ints[i];
        }
        return result;
    }

    /**
     * Creates a double[] array from a String. It is assumed that the double array is encoded like using {@link #toString(double[])}
     *
     * @param data
     * @return
     */
    public static double[] toDoubleArray(String data) {
        LinkedList<Double> dl = new LinkedList<Double>();
        StringTokenizer st = new StringTokenizer(data);
        while (st.hasMoreTokens()) {
            dl.add(Double.parseDouble(st.nextToken()));
        }
        double[] result = new double[dl.size()];
        int count = 0;
        for (Iterator<Double> iterator = dl.iterator(); iterator.hasNext();) {
            double next = iterator.next();
            result[count] = next;
            count++;
        }
        return result;
    }

    /**
     * Converts a byte array with 4 elements to a double. Used to put doubles into a byte[] payload in a convenient
     * and fast way by shifting without using streams (which is kind of slow). Use Note that there is a loss
     * in precision as the double is converted to a float in the course of conversion.
     *
     * @param data the input byte array
     * @return the resulting float
     */
    public static double toDouble(byte[] data) {
        return Double.longBitsToDouble(toLong(data));
    }

    /**
     * Converts a byte[] array with size 8 to a long. <br/>
     * Taken from http://www.daniweb.com/software-development/java/code/216874
     *
     * @param data the byte[] array to convert
     * @return the resulting long.
     * @see #toBytes(long)
     */
    public static long toLong(byte[] data) {
        if (data == null || data.length != 8)
            return 0x0;
        // ----------
        return (long) (
        // (Below) convert to longs before shift because digits
        //         are lost with ints beyond the 32-bit limit
        (long) (0xff & data[0]) << 56 | (long) (0xff & data[1]) << 48 | (long) (0xff & data[2]) << 40
                | (long) (0xff & data[3]) << 32 | (long) (0xff & data[4]) << 24 | (long) (0xff & data[5]) << 16
                | (long) (0xff & data[6]) << 8 | (long) (0xff & data[7]) << 0);
    }
}

Java Array Convert to toDoubleArray(byte[] data)

Description

License

Parameter

Declaration

Method Source Code

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