Example usage for weka.core Instance setValueSparse

Introduction

In this page you can find the example usage for weka.core Instance setValueSparse.

Prototype

public void setValueSparse(int indexOfIndex, double value);

Source Link

Document

Sets a specific value in the instance to the given value (internal floating-point format), given an index into the sparse representation.

Usage

From source file:classifier.CustomStringToWordVector.java

License:Open Source License

/**
 * Normalizes given instance to average doc length (only the newly
 * constructed attributes)./*from  w w w.  j  av a 2  s  .c  o m*/
 * 
 * @param inst
 *            the instance to normalize
 * @param firstCopy
 * @throws Exception
 *             if avg. doc length not set
 */
private void normalizeInstance(Instance inst, int firstCopy) throws Exception {

    double docLength = 0;

    if (m_AvgDocLength < 0) {
        throw new Exception("Average document length not set.");
    }

    // Compute length of document vector
    for (int j = 0; j < inst.numValues(); j++) {
        if (inst.index(j) >= firstCopy) {
            docLength += inst.valueSparse(j) * inst.valueSparse(j);
        }
    }
    docLength = Math.sqrt(docLength);

    // Normalize document vector
    for (int j = 0; j < inst.numValues(); j++) {
        if (inst.index(j) >= firstCopy) {
            double val = inst.valueSparse(j) * m_AvgDocLength / docLength;
            inst.setValueSparse(j, val);
            if (val == 0) {
                System.err.println("setting value " + inst.index(j) + " to zero.");
                j--;
            }
        }
    }
}

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From source file:cluster.ABC.ClusterUtils.java

License:Open Source License

/** Normalizes the values of a SparseInstance in L2 norm
 *
 * @author Sugato Basu//  w  ww.j a  v  a  2 s  .  c o m
 * @param inst SparseInstance to be normalized
 */

public static void normalizeSparseInstance(Instance inst) throws Exception {
    double norm = 0;
    int length = inst.numValues();

    if (!(inst instanceof SparseInstance)) {
        System.err.println("Not SparseInstance, using normalizeInstance function instead");
        normalizeInstance(inst);
    }

    for (int i = 0; i < length; i++) {
        if (inst.index(i) != inst.classIndex()) { // don't normalize the class index
            norm += inst.valueSparse(i) * inst.valueSparse(i);
        }
    }
    norm = Math.sqrt(norm);
    for (int i = 0; i < length; i++) { // don't normalize the class index
        if (inst.index(i) != inst.classIndex()) {
            inst.setValueSparse(i, inst.valueSparse(i) / norm);
        }
    }
}

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From source file:cluster.ABC.ClusterUtils.java

License:Open Source License

/** This function divides every attribute value in an instance by
 *  the instance weight -- useful to find the mean of a cluster in
 *  Euclidean space // w ww. jav a 2 s .  c o  m
 *  @param inst Instance passed in for normalization (destructive update)
 */
public static void normalizeByWeight(Instance inst) {
    double weight = inst.weight();
    if (inst instanceof SparseInstance) {
        for (int i = 0; i < inst.numValues(); i++) {
            inst.setValueSparse(i, inst.valueSparse(i) / weight);
        }
    } else if (!(inst instanceof SparseInstance)) {
        for (int i = 0; i < inst.numAttributes(); i++) {
            inst.setValue(i, inst.value(i) / weight);
        }
    }
}

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From source file:cn.edu.xjtu.dbmine.StringToWordVector.java

License:Open Source License

/**
 * Normalizes given instance to average doc length (only the newly
 * constructed attributes)./*from   w  w  w . j a v  a  2 s .  c  o  m*/
 * 
 * @param inst
 *            the instance to normalize
 * @param firstCopy
 * @throws Exception
 *             if avg. doc length not set
 */

private void normalizeInstance(Instance inst, int firstCopy) throws Exception {

    double docLength = 0;

    if (m_AvgDocLength < 0) {
        throw new Exception("Average document length not set.");
    }

    // Compute length of document vector
    for (int j = 0; j < inst.numValues(); j++) {
        if (inst.index(j) >= firstCopy) {
            docLength += inst.valueSparse(j) * inst.valueSparse(j);
        }
    }
    docLength = Math.sqrt(docLength);

    // Normalize document vector
    for (int j = 0; j < inst.numValues(); j++) {
        if (inst.index(j) >= firstCopy) {
            double val = inst.valueSparse(j) * m_AvgDocLength / docLength;
            inst.setValueSparse(j, val);
            if (val == 0) {
                System.err.println("setting value " + inst.index(j) + " to zero.");
                j--;
            }
        }
    }
}

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