Java List Median calculateMAD(List values, Number median)

Description

calculate MAD

License

Open Source License

Declaration

public static double calculateMAD(List<? extends Number> values, Number median) 

Method Source Code

//package com.java2s;
/**//  w w  w. ja v a 2s .  com
 * This file is part of SADL, a library for learning all sorts of (timed) automata and performing sequence-based anomaly detection.
 * Copyright (C) 2013-2016  the original author or authors.
 *
 * SADL 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 3 of the License, or (at your option) any later version.
 *
 * SADL 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 SADL.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

public class Main {
    public static double calculateMAD(List<? extends Number> values, Number median) {

        double result = Double.NaN;
        if (values != null && median != null) {
            final List<Double> diffs = new ArrayList<Double>(values.size());
            for (int i = 0; i < values.size(); i++) {
                diffs.add(Math.abs(values.get(i).doubleValue() - median.doubleValue()));
            }
            Collections.sort(diffs);
            final int count = diffs.size();
            if (count > 0) {
                if (count % 2 == 1) {
                    if (count > 1) {
                        result = diffs.get((count - 1) / 2).doubleValue();
                    } else {
                        result = diffs.get(0).doubleValue();
                    }
                } else {
                    final double value1 = diffs.get(count / 2 - 1);
                    final double value2 = diffs.get(count / 2);
                    result = (value1 + value2) / 2.0;
                }
            }
        }
        return result;
    }

    public static double calculateMAD(List<Double> values, boolean copyAndSort) {

        double result = Double.NaN;
        if (values != null) {
            final double median = calculateMedian(values, copyAndSort);
            result = calculateMAD(values, median);
        }
        return result;
    }

    /**
     * Calculates the median for a list of values (<code>Number</code> objects). If <code>copyAndSort</code> is <code>false</code>, the list is assumed to be
     * presorted in ascending order by value.
     * 
     * @param values
     *            the values (<code>null</code> permitted).
     * @param copyAndSort
     *            a flag that controls whether the list of values is copied and sorted.
     * 
     * @return The median.
     */
    public static double calculateMedian(List<Double> values, boolean copyAndSort) {

        double result = Double.NaN;
        if (values != null) {
            if (copyAndSort) {
                final List<Double> copy = new ArrayList<Double>(values);
                Collections.sort(copy);
                values = copy;
            }
            result = calcMedian(values, 0, values.size() - 1);
        }
        return result;
    }

    private static double calcMedian(List<Double> values, int start, int end) {

        double result = Double.NaN;
        final int count = end - start + 1;
        if (count > 0) {
            if (count % 2 == 1) {
                if (count > 1) {
                    result = values.get(start + ((count - 1) / 2)).doubleValue();
                } else {
                    result = values.get(start).doubleValue();
                }
            } else {
                final Number value1 = values.get(start + ((count / 2) - 1));
                final Number value2 = values.get(start + (count / 2));
                result = (value1.doubleValue() + value2.doubleValue()) / 2.0;
            }
        }
        return result;
    }
}

Related

1. calcMedian(List values, int start, int end)
2. calculateMedian(List values)
3. calculateMedian(List values, boolean copyAndSort)
4. getGeneMedian(final List doubleArray)
5. getMedian(Collection list)