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:acromusashi.stream.ml.clustering.kmeans.KmeansCalculator.java

/**
 * KMeans++?????//from ww  w  . ja  va2 s  .c o m
 * 
 * @param basePoints ??
 * @param clusterNum 
 * @return 
 */
public static List<KmeansPoint> createInitialCentroids(List<KmeansPoint> basePoints, int clusterNum) {
    Random random = new Random();
    List<KmeansPoint> resultList = Lists.newArrayList();
    // ??????????
    List<KmeansPoint> pointList = Lists.newArrayList(basePoints);
    KmeansPoint firstCentroid = pointList.remove(random.nextInt(pointList.size()));
    resultList.add(firstCentroid);

    double[] dxs;
    // KMeans++??????
    // ??1????????1????
    for (int centroidIndex = 1; centroidIndex < clusterNum; centroidIndex++) {
        // ?????????????
        dxs = computeDxs(pointList, resultList);

        // ??????????
        double r = random.nextDouble() * dxs[dxs.length - 1];
        int next = Arrays.binarySearch(dxs, r);
        int index = 0;
        if (next > 0) {
            index = next - 1;
        } else if (next < 0) {
            index = COMPENSATE_INDEX - next;
        }

        while (index > 0 && resultList.contains(pointList.get(index))) {
            index = index - 1;
        }

        resultList.add(pointList.get(index));
    }

    return resultList;
}

---

From source file:eu.crisis_economics.abm.markets.clearing.heterogeneous.LineSearchTest.java

@Test
/**/*  ww  w.j  a  v  a2s.c  o m*/
  * Test the Brent line search algorithm by minimizing a multidimensional
  * quadratic scalar function. This test generates many random quadratic 
  * fields with random global minima. In each case, the starting point
  * of the minimization is random and the line search direction points 
  * toward the global minimum.
  */
public void batchTestMultidimensionalQuadraticLineSearch() {
    final Random dice = new Random();
    for (int i = 0; i < 100; ++i) { // 100 random quadratic minimization tests
        final int numDimensions = dice.nextInt(20) + 2;
        final double[] globalMinimum = new double[numDimensions], startingPoint = new double[numDimensions];
        for (int j = 0; j < globalMinimum.length; ++j) {
            globalMinimum[j] = dice.nextDouble() * 10. - 5.;
            startingPoint[j] = dice.nextDouble() * 10. - 5.;
        }
        testMultiDimensionalQuadraticMinimization(numDimensions, startingPoint, globalMinimum);
    }
}

---

From source file:net.thumbtack.test.client.JsonQueryClientThread.java

public JsonQueryClientThread(CouchbaseClient _client, GlobalConfig config, long _insertStart, long _insertEnd) {
    this.client = _client;
    this.operationCount = config.getOperationCount();
    this.insertStart = _insertStart;
    this.insertEnd = _insertEnd;
    this.pageSize = config.getPageSize();
    this.queryIndex = config.getQueryIndex();
    this.pageNumber = config.getPageNumber();
    OperationType operationType = config.getOperationType();
    switch (operationType) {
    case INSERT: {
        func = new Func() {
            public void run() throws JsonProcessingException {
                for (long i = insertStart; i < insertEnd; i++) {
                    VendorDoc vendorDoc = new VendorDoc(i);
                    long time = System.currentTimeMillis();
                    client.insert(String.valueOf(i), om.writeValueAsString(vendorDoc));
                    respTimes.add(time - System.currentTimeMillis());
                }//www .  j a v  a  2 s. co m
            }
        };
        break;
    }
    case READ: {
        func = new Func() {
            public void run() {
                Random randomKey = new Random();
                for (int i = 0; i < operationCount; i++) {
                    long time = System.currentTimeMillis();
                    client.read(String
                            .valueOf((int) (randomKey.nextDouble() * (insertEnd - insertStart) + insertStart)));
                    respTimes.add(time - System.currentTimeMillis());
                }
            }
        };
        break;
    }
    case UPDATE: {
        func = new Func() {
            public void run() throws JsonProcessingException {
                Random randomKey = new Random();
                for (long i = 0; i < operationCount; i++) {
                    VendorDoc vendorDoc = new VendorDoc(i);
                    long time = System.currentTimeMillis();
                    client.update(
                            String.valueOf(
                                    (int) (randomKey.nextDouble() * (insertEnd - insertStart) + insertStart)),
                            om.writeValueAsString(vendorDoc));
                    respTimes.add(time - System.currentTimeMillis());
                }
            }
        };
        break;
    }
    case QUERY: {
        func = new Func() {
            public void run() throws JsonProcessingException {
                Random randomKey = new Random();
                for (long i = 0; i < operationCount; i++) {
                    int viewIndex = queryIndex != -1 ? queryIndex
                            : (int) (randomKey.nextDouble() * viewNames.length);
                    int page = pageNumber != -1 ? pageNumber : (int) (randomKey.nextDouble() * 100);
                    long timeElasped;
                    Object key = getViewKey(viewIndex);
                    if (viewIndex < 3) {
                        timeElasped = client.searchInView(viewNames[viewIndex], key, true, pageSize, page);
                    } else {
                        timeElasped = client.searchInSortedView(viewNames[viewIndex], key, true, pageSize,
                                page);
                    }
                    respTimes.add(timeElasped);
                }
            }
        };
        break;
    }
    case N1QL: {
        func = new Func() {
            public void run() throws JsonProcessingException {
                Random randomKey = new Random();
                for (long i = 0; i < operationCount; i++) {
                    int viewIndex = queryIndex != -1 ? queryIndex
                            : (int) (randomKey.nextDouble() * queries.length);
                    long timeElasped = client.searchN1QL(getN1qlQuery(viewIndex) + " limit " + pageSize);
                    respTimes.add(timeElasped);
                }
            }
        };
        break;
    }
    default: {
        throw new UnsupportedOperationException(operationType.toString());
    }
    }
}

---

From source file:se.llbit.math.Ray.java

/**
 * Scatter ray normal/*from w ww . j  a  v  a 2s  . c  om*/
 * @param random random number source
 */
public final void scatterNormal(Random random) {
    // get random point on unit disk
    double x1 = random.nextDouble();
    double x2 = random.nextDouble();
    double r = FastMath.sqrt(x1);
    double theta = 2 * Math.PI * x2;

    // project to point on hemisphere in tangent space
    double tx = r * FastMath.cos(theta);
    double ty = r * FastMath.sin(theta);
    double tz = FastMath.sqrt(1 - x1);

    // transform from tangent space to world space
    double xx, xy, xz;
    double ux, uy, uz;
    double vx, vy, vz;

    if (QuickMath.abs(n.x) > .1) {
        xx = 0;
        xy = 1;
        xz = 0;
    } else {
        xx = 1;
        xy = 0;
        xz = 0;
    }

    ux = xy * n.z - xz * n.y;
    uy = xz * n.x - xx * n.z;
    uz = xx * n.y - xy * n.x;

    r = 1 / FastMath.sqrt(ux * ux + uy * uy + uz * uz);

    ux *= r;
    uy *= r;
    uz *= r;

    vx = uy * n.z - uz * n.y;
    vy = uz * n.x - ux * n.z;
    vz = ux * n.y - uy * n.x;

    n.set(ux * tx + vx * ty + n.x * tz, uy * tx + vy * ty + n.y * tz, uz * tx + vz * ty + n.z * tz);
}

---

From source file:se.llbit.chunky.renderer.scene.Sun.java

/**
 * Point ray in random direction within sun solid angle
 * @param reflected/*from   w  ww  . j  a  v a 2 s  .c  om*/
 * @param random
 */
public void getRandomSunDirection(Ray reflected, Random random) {
    double x1 = random.nextDouble();
    double x2 = random.nextDouble();
    double cos_a = 1 - x1 + x1 * RADIUS_COS;
    double sin_a = FastMath.sqrt(1 - cos_a * cos_a);
    double phi = 2 * Math.PI * x2;

    Vector3d u = new Vector3d(su);
    Vector3d v = new Vector3d(sv);
    Vector3d w = new Vector3d(sw);

    u.scale(FastMath.cos(phi) * sin_a);
    v.scale(FastMath.sin(phi) * sin_a);
    w.scale(cos_a);

    reflected.d.add(u, v);
    reflected.d.add(w);
    reflected.d.normalize();
}

---

From source file:eu.crisis_economics.abm.markets.clearing.heterogeneous.LineSearchTest.java

@Test
/**/*  w  w w. j  av a2 s.c o m*/
  * Test the Brent line search algorithm by minimizing a negative
  * multidimensional quadratic scalar function, with maximum at the
  * origin. This test generated many random boundary boxes (limits
  * inside of which to perform line searches) and, in each case, 
  * extremizes the quadratic function along a random direction starting
  * at the origin. It is expected that the solution lies on the domain
  * bounds in each case.
  */
public void batchTestBoundedDecreasingMultidimensionalSearch() {
    final Random dice = new Random();
    for (int i = 0; i < 100; ++i) { // 100 random tests
        final int numDimensions = dice.nextInt(20) + 2;
        final double[] lowerDomainBounds = new double[numDimensions],
                upperDomainBounds = new double[numDimensions];
        for (int j = 0; j < numDimensions; ++j) {
            lowerDomainBounds[j] = -dice.nextDouble();
            upperDomainBounds[j] = +dice.nextDouble();
        }
        testOptimizationWithDomainBounds(numDimensions, lowerDomainBounds, upperDomainBounds);
    }
}

---

From source file:com.facebook.presto.operator.aggregation.AbstractTestApproximateAggregationFunction.java

private void testCorrectnessOfErrorFunction(List<Number> inputList) throws Exception {
    int inRange = 0;
    int numberOfRuns = 1000;
    double sampleRatio = 1 / (double) WEIGHT;
    double actual = getExpectedValue(inputList);
    Random rand = new Random(1);

    for (int i = 0; i < numberOfRuns; i++) {
        //Compute Sampled Value using sampledList (numberOfRuns times)
        ImmutableList.Builder<Number> sampledList = ImmutableList.builder();
        for (Number x : inputList) {
            if (rand.nextDouble() < sampleRatio) {
                sampledList.add(x);//w  w  w  .  j a  v a 2 s  .c  o m
            }
        }

        ImmutableList<Number> list = sampledList.build();
        BlockBuilder builder = getType().createBlockBuilder(new BlockBuilderStatus(), list.size());
        for (Number sample : list) {
            if (getType().equals(BIGINT)) {
                BIGINT.writeLong(builder, sample.longValue());
            } else if (getType().equals(DOUBLE)) {
                DOUBLE.writeDouble(builder, sample.doubleValue());
            } else {
                throw new AssertionError("Can only handle longs and doubles");
            }
        }
        Page page = new Page(builder.build());
        page = OperatorAssertion.appendSampleWeight(ImmutableList.of(page), WEIGHT).get(0);
        Accumulator accumulator = getFunction().bind(ImmutableList.of(0), Optional.empty(),
                Optional.of(page.getChannelCount() - 1), getConfidence()).createAccumulator();

        accumulator.addInput(page);
        Block result = getFinalBlock(accumulator);

        String approxValue = BlockAssertions.toValues(accumulator.getFinalType(), result).get(0).toString();
        double approx = Double.parseDouble(approxValue.split(" ")[0]);
        double error = Double.parseDouble(approxValue.split(" ")[2]);

        //Check if actual answer lies within [approxAnswer - error, approxAnswer + error]
        if (Math.abs(approx - actual) <= error) {
            inRange++;
        }
    }

    BinomialDistribution binomial = new BinomialDistribution(numberOfRuns, getConfidence());
    int lowerBound = binomial.inverseCumulativeProbability(0.01);
    int upperBound = binomial.inverseCumulativeProbability(0.99);
    assertTrue(lowerBound < inRange && inRange < upperBound, String
            .format("%d out of %d passed. Expected [%d, %d]", inRange, numberOfRuns, lowerBound, upperBound));
}

---

From source file:org.perfcake.reporting.destinations.ChartDestinationTest.java

@Test
public void basicTest() throws Exception {
    final String tempDir = "target/chart";//TestSetup.createTempDir("test-chart");
    log.info("Created temp directory for chart: " + tempDir);

    final ChartDestination cd = new ChartDestination();
    final ChartDestination cd2 = new ChartDestination();
    cd.setOutputDir(tempDir);/*ww  w . j  a v  a  2 s.c  o m*/
    cd2.setOutputDir(tempDir);
    cd.setXAxis("Time of test");
    cd2.setXAxis("Time of test");
    cd.setYAxis("Iterations per second");
    cd2.setYAxis("Iterations per second");
    cd2.setxAxisType(PeriodType.ITERATION);
    cd.setName("Statistics " + (new SimpleDateFormat("HHmmss")).format(new Date()));
    cd2.setName("Performance " + (new SimpleDateFormat("HHmmss")).format(new Date()));
    cd.setGroup("stats");
    cd2.setGroup("perf");
    cd.setAttributes("Average, Result");
    cd2.setAttributes("Average, Result");

    cd.open();
    cd2.open();

    long base = System.currentTimeMillis();
    final Random rnd = new Random();

    Measurement m = new Measurement(10, System.currentTimeMillis() - base, 1);
    m.set(10.3 + rnd.nextDouble());
    m.set("Average", 9.8 + rnd.nextDouble());
    m.set("warmUp", true);
    cd.report(m);
    cd2.report(m);

    Thread.sleep(100);

    m = new Measurement(10, System.currentTimeMillis() - base, 2);
    m.set(10.3 + rnd.nextDouble());
    m.set("Average", 9.8 + rnd.nextDouble());
    m.set("warmUp", true);
    cd.report(m);
    cd2.report(m);

    Thread.sleep(100);

    m = new Measurement(10, System.currentTimeMillis() - base, 3);
    m.set(10.3 + rnd.nextDouble());
    m.set("Average", 9.8 + rnd.nextDouble());
    m.set("warmUp", true);
    cd.report(m);
    cd2.report(m);

    Thread.sleep(100);

    base = System.currentTimeMillis();
    m = new Measurement(10, System.currentTimeMillis() - base, 1);
    m.set(10.3 + rnd.nextDouble());
    m.set("Average", 9.8 + rnd.nextDouble());
    m.set("warmUp", false);
    cd.report(m);
    cd2.report(m);

    Thread.sleep(100);

    m = new Measurement(13, System.currentTimeMillis() - base, 2);
    m.set(11.1 + rnd.nextDouble());
    m.set("Average", 9.1 + rnd.nextDouble());
    m.set("warmUp", false);
    cd.report(m);
    cd2.report(m);

    Thread.sleep(2000);

    m = new Measurement(100, System.currentTimeMillis() - base, 10);
    m.set(9.2 + rnd.nextDouble());
    m.set("Average", 9.0 + rnd.nextDouble());
    m.set("warmUp", false);
    cd.report(m);
    cd2.report(m);

    cd.close();
    cd2.close();

    final Path dir = Paths.get(tempDir);

    verifyBasicFiles(Paths.get(tempDir));

    Assert.assertTrue(dir
            .resolve(Paths.get("data",
                    "stats" + System.getProperty(PerfCakeConst.NICE_TIMESTAMP_PROPERTY) + ".js"))
            .toFile().exists());
    Assert.assertTrue(dir
            .resolve(Paths.get("data",
                    "stats" + System.getProperty(PerfCakeConst.NICE_TIMESTAMP_PROPERTY) + ".dat"))
            .toFile().exists());
    Assert.assertTrue(dir
            .resolve(Paths.get("data",
                    "stats" + System.getProperty(PerfCakeConst.NICE_TIMESTAMP_PROPERTY) + ".html"))
            .toFile().exists());
    Assert.assertTrue(dir
            .resolve(Paths.get("data",
                    "perf" + System.getProperty(PerfCakeConst.NICE_TIMESTAMP_PROPERTY) + ".js"))
            .toFile().exists());
    Assert.assertTrue(dir
            .resolve(Paths.get("data",
                    "perf" + System.getProperty(PerfCakeConst.NICE_TIMESTAMP_PROPERTY) + ".dat"))
            .toFile().exists());
    Assert.assertTrue(dir
            .resolve(Paths.get("data",
                    "perf" + System.getProperty(PerfCakeConst.NICE_TIMESTAMP_PROPERTY) + ".html"))
            .toFile().exists());
}

---

From source file:org.berlin.batch.bom.DataMessageFinder.java

public List<String> queryConnectRules() {
    // First, a random selection to determine which rule to use //
    final Random rand = new Random(System.currentTimeMillis());
    // 1 = backwards
    // 2 = random values
    // 3(default) = forward
    int rule = 3;
    final double r = rand.nextDouble();
    if (r >= 0.8) {
        rule = 1;/*from w  w w. jav  a2 s . co m*/
    } else if (r <= 0.32) {
        rule = 2;
    } else {
        rule = 3;
    } // End of the if - else //

    if (this.forceRequestRule != -1) {
        rule = this.forceRequestRule;
    }
    final List<String> ruleData = new ArrayList<String>();
    if (2 == rule) {
        // Reversed list //
        for (final String term : POPULAR_TERMS) {
            ruleData.add(term);
        } // End of the for //
        Collections.reverse(ruleData);
    } else if (1 == rule) {
        // Random list //
        final Random rand2 = new Random();
        for (String s : POPULAR_TERMS) {
            final int ni = rand2.nextInt(POPULAR_TERMS.length - 1);
            ruleData.add(POPULAR_TERMS[ni]);
        } // End of the for //
    } else {
        // Forward list //
        for (final String term : POPULAR_TERMS) {
            ruleData.add(term);
        } // End of the for //
    } // End of the if - else //
    return ruleData;
}

---

From source file:org.cellprofiler.subimager.TestImageJHandlerBase.java

/**
 * Make an image value parameter containing a random image
 * /*from w w  w . j  a va 2s .c  o  m*/
 * @param dim dimensions of image
 * @param r an instance of Random that provides the random values
 * @param displayName the name of the display to be created
 * @param fieldName the name of the parameter field to set.
 * @param inputMap put the image here so that it can get posted to Subimager
 * @return an ImageValue parameter set up for the image 
 * 
 * @throws IndexOutOfBoundsException
 */
protected Parameter makeImageValueParameter(int[] dim, Random r, String fieldName, String displayName,
        Map<String, NDImage> inputMap) throws IndexOutOfBoundsException {
    double[] buffer = new double[dim[0] * dim[1]];
    for (int i = 0; i < buffer.length; i++)
        buffer[i] = r.nextDouble();
    NDImage ndimage = new NDImage(buffer, dim);
    String imageID = "IMG" + UUID.randomUUID().toString();
    inputMap.put(imageID, ndimage);
    Parameter p = new Parameter();
    ImageValue iv = new ImageValue();
    iv.setImageName(displayName);
    iv.setImageID(imageID);
    iv.addAxis(AxisType.X);
    iv.addAxis(AxisType.Y);
    p.setImageValue(iv);
    p.setName(fieldName);
    return p;
}

---

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