Java stddev stdDev(Integer[] values)

Description

std Dev

License

Apache License

Declaration

public static Double stdDev(Integer[] values) 

Method Source Code

//package com.java2s;
/*/*from  ww  w .  ja va2  s . co  m*/
   Copyright 2014 Shahriyar Amini
    
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at
    
   http://www.apache.org/licenses/LICENSE-2.0
    
   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 */

public class Main {
    public static Double stdDev(Integer[] values) {
        Double variance = variance(values);

        if (variance == null) {
            return null;
        }

        return Math.sqrt(variance.doubleValue());
    }

    public static Double variance(Integer[] values) {
        Double mean = mean(values);

        if (mean == null) {
            return null;
        }

        double tmp = 0;
        double numIntegers = 0;

        for (Integer i : values) {
            if (i == null) {
                continue;
            }

            tmp += (i.intValue() - mean.doubleValue()) * (i.intValue() - mean.doubleValue());
            numIntegers++;
        }

        return tmp / numIntegers;
    }

    public static Double mean(Integer[] values) {
        if (values == null || values.length <= 0) {
            return null;
        }

        double sum = 0.0;
        double numIntegers = 0;

        for (Integer i : values) {
            if (i == null) {
                continue;
            }

            sum += i.intValue();
            numIntegers++;
        }

        return (sum / numIntegers);
    }
}

Related

1. stddev(double[] observations)
2. stddev(final double[] in, final int start, final int length)
3. stddev(final int[] scores)
4. stddev(float[] data)
5. stddev(int[] values, int start, int length)
6. stddev(long[] samples)
7. stddev(Number[] array, boolean isSample)
8. stdDev(T[] array)
9. stdDeviation(int[] data)