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The S-Space Package is a collection of algorithms for building Semantic Spaces as well as a highly-scalable library for designing new distributional semantics algorithms. Distributional algorithms process text corpora and represent the semantic for words as high dimensional feature vectors. This package also includes matrices, vectors, and numerous clustering algorithms. These approaches are known by many names, such as word spaces, semantic spaces, or distributed semantics and rest upon the Distributional Hypothesis: words that appear in similar contexts have similar meanings.

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/*
 * Copyright 2010 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 .
 */

package edu.ucla.sspace.matrix;

import java.io.File;
import java.io.IOError;
import java.io.IOException;

import java.util.Iterator;


/**
 * An abstraction of a matrix that is stored on disk.  This class provides
 * convenient accessors to the contents of the data and allows other classes
 * that operate on matrices to more easily handle matrix files as parameters and
 * return arguments.
 */
public class MatrixFile implements Iterable {

    /**
     * The file containing the matrix data.
     */
    private final File matrixFile;

    /**
     * The current format of the matrix file
     */
    private final MatrixIO.Format format;

    /**
     * Constucts a {@code MatrixFile} from the provided path and format.
     */
    public MatrixFile(String matrixFile, MatrixIO.Format format) {
        this(new File(matrixFile), format);
    }

    /**
     * Constucts a {@code MatrixFile} from the provided {@code File} and format.
     */
    public MatrixFile(File matrixFile, MatrixIO.Format format) {
        // pre-emptive check that the matrix file is non-null
        if (matrixFile == null)
            throw new NullPointerException("matrix file cannot be null");
        this.matrixFile = matrixFile;
        this.format = format;
    }

    public boolean equals(Object o) {
        if (o instanceof MatrixFile) {
            MatrixFile m = (MatrixFile)o;
            return matrixFile.equals(m.matrixFile) 
                && format.equals(m.format);
        }
        return false;
    }

    /**
     * Returns file containing the matrix data 
     */
    public File getFile() {
        return matrixFile;
    }

    /**
     * Returns the format of the matrix
     */
    public MatrixIO.Format getFormat() {
        return format;
    }

    public int hashCode() {
        return matrixFile.hashCode() ^ format.hashCode();
    }

    /**
     * Returns an iterator over all the entries in the matrix.  The order in
     * which entries are returned is format-specific; no guarantee is provided
     * about the ordering.
     */
    public Iterator iterator() {
        try {
            return MatrixIO.getMatrixFileIterator(matrixFile, format);
        } catch (IOException ioe) {
            throw new IOError(ioe);
        }
    }

    /**
     * Loads the matrix from disk and returns a copy of its data.  Note that a
     * new {@code Matrix} is created each time this is called.
     */
    public Matrix load() {
        try {
            return MatrixIO.readMatrix(matrixFile, format);
        } catch (IOException ioe) {
            throw new IOError(ioe);
        }
    }

    public String toString() {
        return "Matrix[" + matrixFile + ":" + format + "]";
    }

}