Example usage for org.apache.mahout.math Vector isSequentialAccess

Introduction

In this page you can find the example usage for org.apache.mahout.math Vector isSequentialAccess.

Prototype

boolean isSequentialAccess();

Source Link

Document

true if this implementation should be considered to be iterable in index order in an efficient way.

Usage

From source file:com.ydy.cf.solver.impl.AlternatingLeastSquaresSolver.java

License:Apache License

private Matrix createRiIiMaybeTransposed(Vector ratingVector) {
    Preconditions.checkArgument(ratingVector.isSequentialAccess());
    Matrix RiIiMaybeTransposed = new DenseMatrix(ratingVector.getNumNondefaultElements(), 1);
    Iterator<Vector.Element> ratingsIterator = ratingVector.iterateNonZero();
    int index = 0;
    while (ratingsIterator.hasNext()) {
        Vector.Element elem = ratingsIterator.next();
        RiIiMaybeTransposed.setQuick(index++, 0, elem.get());
    }//w  w  w.ja v  a  2  s . co  m
    return RiIiMaybeTransposed;
}

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From source file:edu.rosehulman.mahout.math.VectorWritable.java

License:Apache License

public static void writeVector(DataOutput out, Vector vector, boolean laxPrecision) throws IOException {
    boolean dense = vector.isDense();
    boolean sequential = vector.isSequentialAccess();
    boolean named = vector instanceof NamedVector;

    out.writeByte((dense ? FLAG_DENSE : 0) | (sequential ? FLAG_SEQUENTIAL : 0) | (named ? FLAG_NAMED : 0)
            | (laxPrecision ? FLAG_LAX_PRECISION : 0));

    Varint.writeUnsignedVarInt(vector.size(), out);
    if (dense) {//from  w w  w .  j ava2s  .  co  m
        for (Vector.Element element : vector.all()) {
            if (laxPrecision) {
                out.writeFloat((float) element.get());
            } else {
                out.writeDouble(element.get());
            }
        }
    } else {
        Varint.writeUnsignedVarInt(vector.getNumNonZeroElements(), out);
        Iterator<Element> iter = vector.nonZeroes().iterator();
        if (sequential) {
            int lastIndex = 0;
            while (iter.hasNext()) {
                Vector.Element element = iter.next();
                if (element.get() == 0) {
                    continue;
                }
                int thisIndex = element.index();
                // Delta-code indices:
                Varint.writeUnsignedVarInt(thisIndex - lastIndex, out);
                lastIndex = thisIndex;
                if (laxPrecision) {
                    out.writeFloat((float) element.get());
                } else {
                    out.writeDouble(element.get());
                }
            }
        } else {
            while (iter.hasNext()) {
                Vector.Element element = iter.next();
                if (element.get() == 0) {
                    // TODO(robinanil): Fix the damn iterator for the zero element.
                    continue;
                }
                Varint.writeUnsignedVarInt(element.index(), out);
                if (laxPrecision) {
                    out.writeFloat((float) element.get());
                } else {
                    out.writeDouble(element.get());
                }
            }
        }
    }
    if (named) {
        String name = ((NamedVector) vector).getName();
        out.writeUTF(name == null ? "" : name);
    }
}

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