Retrive the quartile value from an array

      
import java.util.Arrays;


/**
 * <p>Static methods for doing useful math</p><hr>
 *
 * @author  : $Author: brian $
 * @version : $Revision: 1.1 $
 *
 * <hr><p><font size="-1" color="#336699"><a href="http://www.mbari.org">
 * The Monterey Bay Aquarium Research Institute (MBARI)</a> provides this
 * documentation and code &quot;as is&quot;, with no warranty, express or
 * implied, of its quality or consistency. It is provided without support and
 * without obligation on the part of MBARI to assist in its use, correction,
 * modification, or enhancement. This information should not be published or
 * distributed to third parties without specific written permission from
 * MBARI.</font></p><br>
 *
 * <font size="-1" color="#336699">Copyright 2002 MBARI.<br>
 * MBARI Proprietary Information. All rights reserved.</font><br><hr><br>
 *
 */

public class Util{
    /**
     * Retrive the quartile value from an array
     * .
     * @param values THe array of data
     * @param lowerPercent The percent cut off. For the lower quartile use 25,
     *      for the upper-quartile use 75
     * @return
     */
    public static double quartile(double[] values, double lowerPercent) {

        if (values == null || values.length == 0) {
            throw new IllegalArgumentException("The data array either is null or does not contain any data.");
        }

        // Rank order the values
        double[] v = new double[values.length];
        System.arraycopy(values, 0, v, 0, values.length);
        Arrays.sort(v);

        int n = (int) Math.round(v.length * lowerPercent / 100);
        
        return v[n];

    }
}

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Retrive the quartile value from an array : Array Compare « Collections Data Structure « Java

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