Example usage for org.apache.mahout.math MatrixSlice nonZeroes

Introduction

In this page you can find the example usage for org.apache.mahout.math MatrixSlice nonZeroes.

Prototype

@Override
    public Iterable<Element> nonZeroes() 

Source Link

Usage

From source file:edu.snu.dolphin.bsp.examples.ml.algorithms.clustering.em.EMMainCmpTask.java

License:Apache License

/**
 * Return a new matrix containing the product of each value of the recipient and the argument.
 * This method exploits sparsity of the matrix, that is, considers only non-zero entries.
 *//*from  w  w w  . java  2 s .  c o m*/
private Matrix times(final Matrix matrix, final double scala) {
    final Matrix result = matrix.clone();
    final Iterator<MatrixSlice> sliceIterator = matrix.iterator();
    while (sliceIterator.hasNext()) {
        final MatrixSlice slice = sliceIterator.next();
        final int row = slice.index();
        for (final Vector.Element e : slice.nonZeroes()) {
            final int col = e.index();
            result.set(row, col, e.get() * scala);
        }
    }
    return result;
}

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From source file:edu.snu.dolphin.bsp.examples.ml.data.ClusterStats.java

License:Apache License

/**
 * Compute the covariance matrix from the statistics.
 * @return//  w ww. ja va2s.  c  o m
 */
public Matrix computeCovariance() {
    final Vector mean = computeMean();
    final Matrix covariance = outProdSum.clone();

    final Iterator<MatrixSlice> sliceIterator = outProdSum.iterator();
    while (sliceIterator.hasNext()) {
        final MatrixSlice slice = sliceIterator.next();
        final int row = slice.index();
        for (final Vector.Element e : slice.nonZeroes()) {
            final int col = e.index();
            final double squaredSum = e.get();
            covariance.set(row, col, squaredSum / probSum - mean.get(row) * mean.get(col));
        }
    }
    return covariance;
}

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