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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.dv;

import edu.ucla.sspace.basis.AbstractBasisMapping;

import edu.ucla.sspace.dependency.DependencyPath;

import java.util.HashSet;
import java.util.Set;


/**
 * A {@link BasisMapping} implementation where each word corresponds to a unique
 * dimension regardless of how it is grammatically related.  For example "clock"
 * occuring with the "{@code SBJ}" relation will have the same dimension as
 * "clock" occurring with the "{@code OBJ}" relation.
 *
 * @author David Jurgens
 */
public class WordBasedBasisMapping
    extends AbstractBasisMapping 
    implements DependencyPathBasisMapping {

    private static final long serialVersionUID = 1L;

    private final Set excludedFeatures;

    public WordBasedBasisMapping() {
        excludedFeatures = null;
    }

    public WordBasedBasisMapping(Set excludedFeatures) {
        this.excludedFeatures = excludedFeatures;
    }

    /**
     * Returns the dimension number corresponding to the term at the end of the
     * provided path.
     *
     * @param path a path whose end represents a semantic connection
     *
     * @return the dimension for the occurrence of the last word in the path
     */
    public int getDimension(DependencyPath path) {       
        String word = path.last().word();
        return (excludedFeatures == null || !excludedFeatures.contains(word))
            ? getDimensionInternal(word)
            : -1;
    }
}