Java Collection Mean getVariance(Collection data, Number mean)

Description

Returns the standard deviation of a set of numbers.

License

Open Source License

Parameter

Parameter	Description
data	the data (<code>null</code> or zero length array not permitted).

Return

The standard deviation of a set of numbers.

Declaration

public static double getVariance(Collection<? extends Number> data, Number mean) 

Method Source Code

//package com.java2s;
/**//from   ww  w . jav a 2 s  .c o  m
 * 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.Collection;

import java.util.Iterator;

public class Main {
    /**
     * Returns the standard deviation of a set of numbers.
     * 
     * @param data
     *            the data (<code>null</code> or zero length array not permitted).
     * 
     * @return The standard deviation of a set of numbers.
     */
    public static double getVariance(Collection<? extends Number> data, Number mean) {

        double result = Double.NaN;
        if (data != null && data.size() > 0 && mean != null) {
            double sum = 0.0;
            for (final Number n : data) {
                final double diff = n.doubleValue() - mean.doubleValue();
                sum = sum + (diff * diff);
            }
            result = sum / (data.size());
        }
        return result;
    }

    public static double getVariance(Collection<? extends Number> data) {

        final double avg = calculateMean(data);
        return getVariance(data, avg);
    }

    /**
     * Returns the mean of a collection of {@link Number} objects.
     * 
     * @param values
     *            {@link Collection} of values; elements may not be {@code null}; {@code NaN} and infinite values will be ignored
     * 
     * @return The mean of the given {@link Collection}
     */
    public static double calculateMean(Collection<? extends Number> values) {

        int count = 0;
        double total = 0.0;
        final Iterator<? extends Number> iterator = values.iterator();
        while (iterator.hasNext()) {
            final double value = iterator.next().doubleValue();
            if (!Double.isNaN(value) && !Double.isInfinite(value)) {
                total += value;
                count++;
            }
        }
        return total / count;
    }
}

Related

1. calculateMean(Collection values)
2. calculateMean(Collection values)
3. getMean(Collection data)
4. getMean(Collection cluster)
5. getMean(final Collection collection)
6. mean(Collection coll)
7. mean(Collection nums)
8. mean(Collection data)
9. mean(Collection dist)