Examples of Skewness

org.apache.commons.math.stat.descriptive.moment.Skewness

Computes the skewness of the available values.

We use the following (unbiased) formula to define skewness:

skewness = [n / (n -1) (n - 2)] sum[(x_i - mean)^3] / std^3

where n is the number of values, mean is the {@link Mean} and std is the{@link StandardDeviation}

Note that this implementation is not synchronized. If multiple threads access an instance of this class concurrently, and at least one of the threads invokes the increment() or clear() method, it must be synchronized externally.

@version $Revision: 1006299 $ $Date: 2010-10-10 16:47:17 +0200 (dim. 10 oct. 2010) $

org.apache.commons.math.stat.univariate.moment.Skewness

@version $Revision: 1.14 $ $Date: 2003/11/19 03:28:24 $

org.apache.commons.math3.stat.descriptive.moment.Skewness

Computes the skewness of the available values.

We use the following (unbiased) formula to define skewness:

skewness = [n / (n -1) (n - 2)] sum[(x_i - mean)^3] / std^3

where n is the number of values, mean is the {@link Mean} and std is the{@link StandardDeviation}

        long start = Long.MAX_VALUE;
        long finish = 0;
        
        Mean mean = new Mean();
        StandardDeviation stdDev = new StandardDeviation();
        Skewness skewness = new Skewness();
        
        int n = 0;
        for(Sample sample: samples) {
            if (threadNo == -1 || threadNo == sample.threadId) {
                n++;
                if (sample.timestamp < start) {
                    start = sample.timestamp;
                }
                if (sample.timestamp + sample.duration > finish) {
                    finish = sample.timestamp + sample.duration;
                }
                mean.increment(sample.duration);
                stdDev.increment(sample.duration);
                skewness.increment(sample.duration);
            }
        }
        
        double throughPut = (double)n * (double)TimeUnit.SECONDS.toNanos(1) / (double)(finish - start);
        
        System.out.println(String.format("Mean(NS)    %.1f", mean.getResult()));
        System.out.println(String.format("StdDev(NS)  %.1f", stdDev.getResult()));
        System.out.println(String.format("Skew(NS)    %.1f", skewness.getResult()));
        System.out.println(String.format("Throughput  %.1f", throughPut));
        System.out.println(String.format("Total time  %.3f", (finish - start) / (double)TimeUnit.SECONDS.toNanos(1)));
        
    }

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Examples of Skewness

Examples of org.apache.commons.math3.stat.descriptive.moment.Skewness