Example usage for org.apache.mahout.math.function DoubleFunction apply

Introduction

In this page you can find the example usage for org.apache.mahout.math.function DoubleFunction apply.

Prototype

public abstract double apply(double x);

Source Link

Document

Apply the function to the argument and return the result

Usage

From source file:com.mapr.synth.ForeignKeySamplerTest.java

License:Apache License

private void check(int n, DoubleFunction distribution, Sampler<JsonNode> s) {
    int[] counts = new int[n];
    for (int i = 0; i < 100000; i++) {
        counts[s.sample().asInt()]++;/*  ww w  . ja  va 2s.co m*/
    }

    double sum = 0;
    double[] p = new double[n];
    for (int i = 0; i < n; i++) {
        p[i] = distribution.apply(i);
        sum += p[i];
    }

    double z1 = 0;
    double z2 = 0;
    for (int i = 0; i < n; i++) {
        z1 += (p[i] - counts[i] / 100000.0) * Math.log(p[i] / sum);
        double expected = p[i] * 100000;
        double deviation = expected - counts[i];
        z2 += deviation * deviation / expected;
    }
    System.out.printf("%.4f %.4f\n", z1, z2);
}

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From source file:org.carrot2.matrix.MatrixUtils.java

License:Open Source License

/**
 * Common implementation of finding extreme elements in columns.
 *//*w ww.j a  va  2  s . co m*/
private static int[] inColumns(DoubleMatrix2D A, int[] indices, double[] extValues,
        DoubleComparator doubleComparator, DoubleFunction transform) {
    if (indices == null) {
        indices = new int[A.columns()];
    }

    if (A.columns() == 0 || A.rows() == 0) {
        return indices;
    }

    if (extValues == null) {
        extValues = new double[A.columns()];
    }

    for (int c = 0; c < A.columns(); c++) {
        extValues[c] = transform.apply(A.getQuick(0, c));
    }
    Arrays.fill(indices, 0);

    for (int r = 1; r < A.rows(); r++) {
        for (int c = 0; c < A.columns(); c++) {
            final double transformed = transform.apply(A.getQuick(r, c));
            if (doubleComparator.compare(transformed, extValues[c]) > 0) {
                extValues[c] = transformed;
                indices[c] = r;
            }
        }
    }

    return indices;
}

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