Example usage for java.util Random nextDouble

Introduction

In this page you can find the example usage for java.util Random nextDouble.

Prototype

public double nextDouble() 

Source Link

Document

Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

Usage

From source file:eu.amidst.core.exponentialfamily.EF_InverseGamma.java

/**
 * {@inheritDoc}// w ww .ja v  a2 s  . c  o  m
 */
@Override
public EF_UnivariateDistribution randomInitialization(Random random) {
    double alpha = random.nextGaussian() * 2 + 1;
    double beta = random.nextDouble() * 1 + 0.1;

    this.getNaturalParameters().set(0, -alpha - 1);
    this.getNaturalParameters().set(1, -beta);
    this.fixNumericalInstability();
    this.updateMomentFromNaturalParameters();

    return this;
}

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From source file:beast.math.distribution.GammaDistributionTest.java

@Test
public void testPdf() {

    final int numberOfTests = 100;
    double totErr = 0;
    double ptotErr = 0;
    int np = 0;//from   www  . j a  v a 2 s  .  com
    double qtotErr = 0;

    Random random = new Random(37);

    for (int i = 0; i < numberOfTests; i++) {
        final double mean = .01 + (3 - 0.01) * random.nextDouble();
        final double var = .01 + (3 - 0.01) * random.nextDouble();

        final double scale = var / mean;
        final double shape = mean / scale;

        final GammaDistribution gamma = new GammaDistribution(shape, scale);

        final double value = gamma.nextGamma();

        final double mypdf = mypdf(value, shape, scale);
        final double pdf = gamma.pdf(value);
        if (Double.isInfinite(mypdf) && Double.isInfinite(pdf)) {
            continue;
        }

        assertFalse(Double.isNaN(mypdf));
        assertFalse(Double.isNaN(pdf));

        totErr += mypdf != 0 ? Math.abs((pdf - mypdf) / mypdf) : pdf;

        assertFalse("nan", Double.isNaN(totErr));
        //assertEquals("" + shape + "," + scale + "," + value, mypdf,gamma.pdf(value),1e-10);

        final double cdf = gamma.cdf(value);
        UnivariateFunction f = new UnivariateFunction() {
            public double value(double v) {
                return mypdf(v, shape, scale);
            }
        };
        final UnivariateIntegrator integrator = new RombergIntegrator(MachineAccuracy.SQRT_EPSILON, 1e-14, 1,
                16);

        double x;
        try {
            x = integrator.integrate(16, f, 0.0, value);
            ptotErr += cdf != 0.0 ? Math.abs(x - cdf) / cdf : x;
            np += 1;
            //assertTrue("" + shape + "," + scale + "," + value + " " + Math.abs(x-cdf)/x + "> 1e-6", Math.abs(1-cdf/x) < 1e-6);

            //System.out.println(shape + ","  + scale + " " + value);
        } catch (MaxCountExceededException e) {
            // can't integrate , skip test
            //  System.out.println(shape + ","  + scale + " skipped");
        }

        final double q = gamma.quantile(cdf);
        qtotErr += q != 0 ? Math.abs(q - value) / q : value;
        // assertEquals("" + shape + "," + scale + "," + value + " " + Math.abs(q-value)/value, q, value, 1e-6);
    }
    //System.out.println( !Double.isNaN(totErr) );
    // System.out.println(totErr);
    // bad test, but I can't find a good threshold that works for all individual cases 
    assertTrue("failed " + totErr / numberOfTests, totErr / numberOfTests < 1e-7);
    assertTrue("failed " + ptotErr / np, np > 0 ? (ptotErr / np < 1e-5) : true);
    assertTrue("failed " + qtotErr / numberOfTests, qtotErr / numberOfTests < 1e-7);
}

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From source file:org.orekit.utils.FieldAngularCoordinatesTest.java

private FieldRotation<DerivativeStructure> randomRotation(Random random) {
    double q0 = random.nextDouble() * 2 - 1;
    double q1 = random.nextDouble() * 2 - 1;
    double q2 = random.nextDouble() * 2 - 1;
    double q3 = random.nextDouble() * 2 - 1;
    double q = FastMath.sqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
    return createRotation(q0 / q, q1 / q, q2 / q, q3 / q, false);
}

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From source file:edu.cornell.med.icb.goby.algorithmic.algorithm.TestComputeStartCount.java

/**
 * @param lo lower limit of range//from  w w w .j a v  a2s. co m
 * @param hi upper limit of range
 * @return a random integer in the range <STRONG>lo</STRONG>,
 *         <STRONG>lo</STRONG>+1, ... ,<STRONG>hi</STRONG>
 */
private int chooseRandom(Random random, final int lo, final int hi) {
    final double r = random.nextDouble();
    int result = (int) ((long) lo + (long) ((1L + (long) hi - (long) lo) * r));
    assert result >= lo && result <= hi;
    return result;
}

---

From source file:com.caseystella.analytics.distribution.DistributionTest.java

@Test
public void testQuantiles() {
    Random r = new Random(0);
    List<DataPoint> points = new ArrayList<>();
    DescriptiveStatistics stats = new DescriptiveStatistics();
    Distribution distribution = null;//from  www  . ja v  a 2 s. c  o m
    for (int i = 0; i < 100; ++i) {
        double val = r.nextDouble() * 1000;
        DataPoint dp = (new DataPoint(i, val, null, "foo"));
        points.add(dp);
        stats.addValue(val);
        if (distribution == null) {
            distribution = new Distribution(dp, ScalingFunctions.NONE, new GlobalStatistics());
        } else {
            distribution.addDataPoint(dp, ScalingFunctions.NONE);
        }
    }
    double realMedian = stats.getPercentile(50);
    double approxMedian = distribution.getMedian();
    System.out.println("mean and std dev: " + stats.getMean() + ", " + Math.sqrt(stats.getVariance()));
    System.out.println("Real : " + realMedian + ", approx: " + approxMedian);
    Assert.assertTrue(Math.abs(realMedian - approxMedian) < 5);
}

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From source file:it.stilo.g.util.WeightedZIPFianGenerator.java

public void run() {

    Random rnd = new Random(System.currentTimeMillis());

    for (int i = chunk; i < g.out.length; i += runner) {
        for (int j = 0; j < degree; j++) {

            while (!g.testAndAdd(i, dist.sample() - 1, rnd.nextDouble()))
                ;/*from   w  w w.ja  v a  2 s  .c om*/
        }
    }
    barrier.countDown();
}

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From source file:org.geomesa.QuickStart.java

static FeatureCollection createNewFeatures(SimpleFeatureType simpleFeatureType, int numNewFeatures) {
    DefaultFeatureCollection featureCollection = new DefaultFeatureCollection();

    String id;//  www  .  j  a v a  2  s. co  m
    Object[] NO_VALUES = {};
    String[] PEOPLE_NAMES = { "Addams", "Bierce", "Clemens" };
    Long SECONDS_PER_YEAR = 365L * 24L * 60L * 60L;
    Random random = new Random(5771);
    DateTime MIN_DATE = new DateTime(2014, 1, 1, 0, 0, 0, DateTimeZone.forID("UTC"));
    Double MIN_X = -78.0;
    Double MIN_Y = -39.0;
    Double DX = 2.0;
    Double DY = 2.0;

    for (int i = 0; i < numNewFeatures; i++) {
        // create the new (unique) identifier and empty feature shell
        id = "Observation." + Integer.toString(i);
        SimpleFeature simpleFeature = SimpleFeatureBuilder.build(simpleFeatureType, NO_VALUES, id);

        // be sure to tell GeoTools explicitly that you want to use the ID you provided
        simpleFeature.getUserData().put(Hints.USE_PROVIDED_FID, java.lang.Boolean.TRUE);

        // populate the new feature's attributes

        // string value
        simpleFeature.setAttribute("Who", PEOPLE_NAMES[i % PEOPLE_NAMES.length]);

        // long value
        simpleFeature.setAttribute("What", i);

        // location:  construct a random point within a 2-degree-per-side square
        double x = MIN_X + random.nextDouble() * DX;
        double y = MIN_Y + random.nextDouble() * DY;
        Geometry geometry = WKTUtils$.MODULE$.read("POINT(" + x + " " + y + ")");

        // date-time:  construct a random instant within a year
        simpleFeature.setAttribute("Where", geometry);
        DateTime dateTime = MIN_DATE.plusSeconds((int) Math.round(random.nextDouble() * SECONDS_PER_YEAR));
        simpleFeature.setAttribute("When", dateTime.toDate());

        // another string value
        // "Why"; left empty, showing that not all attributes need values

        // accumulate this new feature in the collection
        featureCollection.add(simpleFeature);
    }

    return featureCollection;
}

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From source file:org.orekit.utils.FieldAngularCoordinatesTest.java

private FieldVector3D<DerivativeStructure> randomVector(Random random, double norm) {
    double n = random.nextDouble() * norm;
    double x = random.nextDouble();
    double y = random.nextDouble();
    double z = random.nextDouble();
    return new FieldVector3D<DerivativeStructure>(n, createVector(x, y, z, 4).normalize());
}

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From source file:edu.berkeley.sparrow.examples.HeterogeneousFrontend.java

/**
 * Generates exponentially distributed interarrival delays.
 *//*from   w w w. j  av a 2s. c om*/
public double generateInterarrivalDelay(Random r, double lambda) {
    double u = r.nextDouble();
    return -Math.log(u) / lambda;
}

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From source file:pl.mg6.newmaps.demo.AddMarkersInBackgroundExampleActivity.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.many_markers_example);

    map = GoogleMapHelper.getMap(this, R.id.many_markers_map);

    Random r = new Random();

    long start = SystemClock.uptimeMillis();
    for (int i = 0; i < ManyMarkersExampleActivity.MARKERS_COUNT; i++) {
        LatLng position = new LatLng((r.nextDouble() - 0.5) * 170.0, (r.nextDouble() - 0.5) * 360.0);
        positions[i] = new LatLngDistance(position);
    }/*w ww  .j av  a 2s .  c o m*/
    long end = SystemClock.uptimeMillis();
    Log.w(TAG, "generate time: " + (end - start));
}

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