/*
* Copyright 2009 David Jurgens
*
* This file is part of the S-Space package and is covered under the terms and
* conditions therein.
*
* The S-Space package is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation and distributed hereunder to you.
*
* THIS SOFTWARE IS PROVIDED "AS IS" AND NO REPRESENTATIONS OR WARRANTIES,
* EXPRESS OR IMPLIED ARE MADE. BY WAY OF EXAMPLE, BUT NOT LIMITATION, WE MAKE
* NO REPRESENTATIONS OR WARRANTIES OF MERCHANT- ABILITY OR FITNESS FOR ANY
* PARTICULAR PURPOSE OR THAT THE USE OF THE LICENSED SOFTWARE OR DOCUMENTATION
* WILL NOT INFRINGE ANY THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER
* RIGHTS.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package edu.ucla.sspace.matrix;
import edu.ucla.sspace.vector.SparseDoubleVector;
import edu.ucla.sspace.vector.SparseHashDoubleVector;
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOError;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* An iterator for sequentially accessing the rows of a {@link
* MatrixIO.Format.SVDLIBC_SPARSE_BINARY} formatted file.
*
* @author David Jurgens
*/
class SvdlibcSparseBinaryFileRowIterator
implements Iterator<SparseDoubleVector> {
/**
* The stream of bytes in the matrix file.
*/
private final ByteBuffer data;
/**
* The next {@link SparseDoubleVector} to be returned.
*/
private SparseDoubleVector next;
/**
* The entry number that will next be returned from the matrix
*/
private int entry;
/**
* The total number of non-zero entries in the matrix
*/
private int nzEntriesInMatrix;
/**
* The index of the current column
*/
private int curCol;
/**
* The number of rows in the matrix.
*/
private final int rows;
/**
* The number of columns in the matrix.
*/
private final int cols;
/**
* Creates a new {@link SvdlibcSparseBinaryFileRowIterator} for {@code
* matrixFile}.
*/
public SvdlibcSparseBinaryFileRowIterator(File matrixFile)
throws IOException {
// Create the accessor for the data stream.
RandomAccessFile raf = new RandomAccessFile(matrixFile, "r");
FileChannel fc = raf.getChannel();
data = fc.map(MapMode.READ_ONLY, 0, fc.size());
fc.close();
// Read the number of rows, columns, and non zero entries in the matrix.
this.rows = data.getInt();
this.cols = data.getInt();
nzEntriesInMatrix = data.getInt();
// Initialize the counters.
curCol = 0;
entry = 0;
advance();
}
/**
* Sets {@code next} to be the next row in the data matrix.
*/
private void advance() throws IOException {
if (entry >= nzEntriesInMatrix) {
next = null;
}
else {
// Reads off a new vector from the data file.
next = new SparseHashDoubleVector(rows);
int nzInCol = data.getInt();
for (int i = 0; i < nzInCol; ++i, ++entry) {
int row = data.getInt();
double value = data.getFloat();
next.set(row, value);
}
curCol++;
}
}
/**
* {@inheritDoc}
*/
public boolean hasNext() {
return next != null;
}
/**
* {@inheritDoc}
*/
public SparseDoubleVector next() {
if (next == null)
throw new NoSuchElementException("No futher entries");
SparseDoubleVector curCol = next;
try {
advance();
} catch (IOException ioe) {
throw new IOError(ioe);
}
return curCol;
}
/**
* Throws an {@link UnsupportedOperationException} if called.
*/
public void remove() {
throw new UnsupportedOperationException("Cannot remove from file");
}
/**
* Resets the iterator to the start of the file's data.
*/
public void reset() {
data.rewind();
// Read off the rows, columns, and non-zero elements
data.getInt();
data.getInt();
data.getInt();
// Reset the counters.
curCol = 0;
entry = 0;
try {
advance();
} catch (IOException ioe) {
throw new IOError(ioe);
}
}
}