Example usage for org.apache.commons.math3.random EmpiricalDistribution cumulativeProbability

Introduction

In this page you can find the example usage for org.apache.commons.math3.random EmpiricalDistribution cumulativeProbability.

Prototype

public double cumulativeProbability(double x) 

Source Link

Document

Algorithm description:

1. Find the bin B that x belongs to.
2. Compute P(B) = the mass of B and P(B-) = the combined mass of the bins below B.
3. Compute K(B) = the probability mass of B with respect to the within-bin kernel and K(B-) = the kernel distribution evaluated at the lower endpoint of B
4. Return P(B-) + P(B) * [K(x) - K(B-)] / K(B) where K(x) is the within-bin kernel distribution function evaluated at x.

Usage

From source file:org.apache.solr.client.solrj.io.eval.HistogramEvaluator.java

@Override
public Object doWork(Object... values) throws IOException {
    if (Arrays.stream(values).anyMatch(item -> null == item)) {
        return null;
    }/*from w  w w  . j  a v a 2 s .  c o  m*/

    List<?> sourceValues;
    Integer bins = 10;

    if (values.length >= 1) {
        sourceValues = values[0] instanceof List<?> ? (List<?>) values[0] : Arrays.asList(values[0]);

        if (values.length >= 2) {
            if (values[1] instanceof Number) {
                bins = ((Number) values[1]).intValue();
            } else {
                throw new IOException(String.format(Locale.ROOT,
                        "Invalid expression %s - if second parameter is provided then it must be a valid number but found %s instead",
                        toExpression(constructingFactory), values[1].getClass().getSimpleName()));
            }
        }
    } else {
        throw new IOException(
                String.format(Locale.ROOT, "Invalid expression %s - expecting at least one value but found %d",
                        toExpression(constructingFactory), containedEvaluators.size()));
    }

    EmpiricalDistribution distribution = new EmpiricalDistribution(bins);
    distribution.load(
            ((List<?>) sourceValues).stream().mapToDouble(value -> ((Number) value).doubleValue()).toArray());
    ;

    List<Tuple> histogramBins = new ArrayList<>();
    for (SummaryStatistics binSummary : distribution.getBinStats()) {
        Map<String, Number> map = new HashMap<>();
        map.put("max", binSummary.getMax());
        map.put("mean", binSummary.getMean());
        map.put("min", binSummary.getMin());
        map.put("stdev", binSummary.getStandardDeviation());
        map.put("sum", binSummary.getSum());
        map.put("N", binSummary.getN());
        map.put("var", binSummary.getVariance());
        map.put("cumProb", distribution.cumulativeProbability(binSummary.getMean()));
        map.put("prob", distribution.probability(binSummary.getMin(), binSummary.getMax()));
        histogramBins.add(new Tuple(map));
    }

    return histogramBins;
}

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