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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 Keith Stevens
 *
 * 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.dependency;

import edu.ucla.sspace.index.DefaultPermutationFunction;
import edu.ucla.sspace.index.PermutationFunction;

import edu.ucla.sspace.vector.Vector;

import java.io.Serializable;

import java.util.LinkedList;


/**
 * An default {@link DependencyPermutationFunction} for permuting a {@link
 * Vector} based on a dependecny path, represented as a list of {@link
 * DependencyRelation}s.  A passed in {@link PermutationFunction} is used to
 * permute the {@link Vector}s based on the path length.
 *
 * @see edu.ucla.sspace.index.PermutationFunction
 *
 * @author Keith Stevens
 */
public class RelationPermutationFunction 
        implements DependencyPermutationFunction, Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * The internal {@link PermutationFunction} to use for permuting vectors.
     */
    private final PermutationFunction permFunc;

    /**
     * Creates a new {@link DefaultDependencyPermutationFunction} that wraps an
     * existing {@link PermutationFunction}.
     */
    public RelationPermutationFunction(
            PermutationFunction permFunc) {
        this.permFunc = permFunc;
    }

    /**
     * {@inheritDoc}
     */
    public T permute(T vector, DependencyPath path) {
        int bestRelationScore = 0; 
        for (DependencyRelation link : path) {
            int relationScore = getRelationScore(link.relation());
            if (relationScore > bestRelationScore)
                bestRelationScore = relationScore;
        }
        return permFunc.permute(vector, bestRelationScore);
    }

    private static int getRelationScore(String relation) {
        if (relation.length() == 0)
            return 0;

        if (relation.equals("SBJ"))
            return 6;
        if (relation.equals("OBJ"))
            return 5;
        if (relation.equals("NMOD"))
            return 4;
        if (relation.equals("VMOD"))
            return 3;
        if (relation.equals("ADV"))
            return 2;
        return 1;
    }
}