Examples of SecondMoment

org.apache.commons.math.stat.descriptive.moment.SecondMoment
Computes a statistic related to the Second Central Moment. Specifically, what is computed is the sum of squared deviations from the sample mean.
The following recursive updating formula is used:

Let
- dev = (current obs - previous mean)
- n = number of observations (including current obs)
Then

new value = old value + dev^2 * (n -1) / n.

Returns Double.NaN if no data values have been added and returns 0 if there is just one value in the data set.

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: 811685 $ $Date: 2009-09-05 19:36:48 +0200 (sam. 05 sept. 2009) $
org.apache.commons.math3.stat.descriptive.moment.SecondMoment
Computes a statistic related to the Second Central Moment. Specifically, what is computed is the sum of squared deviations from the sample mean.
The following recursive updating formula is used:

Let
- dev = (current obs - previous mean)
- n = number of observations (including current obs)
Then

new value = old value + dev^2 * (n -1) / n.

Returns Double.NaN if no data values have been added and returns 0 if there is just one value in the data set.

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.

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


    @Test
    public void testMomentSmallSamples() {
        UnivariateStatistic stat = getUnivariateStatistic();
        if (stat instanceof SecondMoment) {
            SecondMoment moment = (SecondMoment) getUnivariateStatistic();
            Assert.assertTrue(Double.isNaN(moment.getResult()));
            moment.increment(1d);
            Assert.assertEquals(0d, moment.getResult(), 0);
        }
    }

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

     */
    public double calculateTotalSumOfSquares() {
        if (isNoIntercept()) {
            return StatUtils.sumSq(getY().toArray());
        } else {
            return new SecondMoment().evaluate(getY().toArray());
        }
    }

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

     */
    public double calculateTotalSumOfSquares() throws MathIllegalArgumentException {
        if (isNoIntercept()) {
            return StatUtils.sumSq(getY().toArray());
        } else {
            return new SecondMoment().evaluate(getY().toArray());
        }
    }

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

     */
    public double calculateTotalSumOfSquares() throws MathIllegalArgumentException {
        if (isNoIntercept()) {
            return StatUtils.sumSq(getY().toArray());
        } else {
            return new SecondMoment().evaluate(getY().toArray());
        }
    }

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


    @Test
    public void testMomentSmallSamples() {
        UnivariateStatistic stat = getUnivariateStatistic();
        if (stat instanceof SecondMoment) {
            SecondMoment moment = (SecondMoment) getUnivariateStatistic();
            Assert.assertTrue(Double.isNaN(moment.getResult()));
            moment.increment(1d);
            Assert.assertEquals(0d, moment.getResult(), 0);
        }
    }

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


    
    @Ignore
    @Test
    public void testSummaryStatisticsJson() throws Exception {
        final SecondMoment secondMoment = new SecondMoment();
        final Sum sum = new Sum();
        final SumOfSquares sumsq = new SumOfSquares();
        final Min min = new Min();
        final Max max = new Max();
        final SumOfLogs sumLog = new SumOfLogs();
        
        final Random r = new Random(0);
        for (int i = 0; i < 10; i++) {
            final int nextInt = r.nextInt(100000000);
            secondMoment.increment(nextInt);
            sum.increment(nextInt);
            sumsq.increment(nextInt);
            min.increment(nextInt);
            max.increment(nextInt);
            sumLog.increment(nextInt);

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

    
    //***** ALL FIELDS ARE LAZILY INITIALIZED HERE *****//
    
    private SecondMoment _getSecondMoment() {
        if (this.secondMoment == null) {
            this.secondMoment = new SecondMoment();
        }
        return this.secondMoment;
    }

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


    @Test
    public void testMomentSmallSamples() {
        UnivariateStatistic stat = getUnivariateStatistic();
        if (stat instanceof SecondMoment) {
            SecondMoment moment = (SecondMoment) getUnivariateStatistic();
            Assert.assertTrue(Double.isNaN(moment.getResult()));
            moment.increment(1d);
            Assert.assertEquals(0d, moment.getResult(), 0);
        }
    }

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