com.jgaap.backend.DistanceFunctions.java Source code

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Here is the source code for com.jgaap.backend.DistanceFunctions.java

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/*
 * JGAAP -- a graphical program for stylometric authorship attribution
 * Copyright (C) 2009,2011 by Patrick Juola
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.jgaap.backend;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.jgaap.generics.DistanceFunction;

/**
 * 
 * Instances new Distance Functions based on display name.
 * If parameters are also passed in the form DisplayName|name:value|name:value they are added to the Distance Function before it is returned
 * 
 * @author Michael Ryan
 * @since 5.0.0
 */

public class DistanceFunctions {

    private static final ImmutableList<DistanceFunction> DISTANCE_FUNCTIONS = loadDistanceFunctions();
    private static final ImmutableMap<String, DistanceFunction> distanceFunctions = loadDistanceFunctionsMap();

    /**
     * A read-only list of the DistanceFunctions
     */
    public static List<DistanceFunction> getDistanceFunctions() {
        return DISTANCE_FUNCTIONS;
    }

    private static ImmutableList<DistanceFunction> loadDistanceFunctions() {
        List<Object> objects = AutoPopulate.findObjects("com.jgaap.distances", DistanceFunction.class);
        for (Object tmp : AutoPopulate.findClasses("com.jgaap.generics", DistanceFunction.class)) {
            objects.addAll(AutoPopulate.findObjects("com.jgaap.distances", (Class<?>) tmp));
        }
        List<DistanceFunction> distances = new ArrayList<DistanceFunction>(objects.size());
        for (Object tmpD : objects) {
            distances.add((DistanceFunction) tmpD);
        }
        Collections.sort(distances);
        return ImmutableList.copyOf(distances);
    }

    private static ImmutableMap<String, DistanceFunction> loadDistanceFunctionsMap() {
        // Load the distance functions dynamically
        ImmutableMap.Builder<String, DistanceFunction> builder = ImmutableMap.builder();
        for (DistanceFunction distanceFunction : DISTANCE_FUNCTIONS) {
            builder.put(distanceFunction.displayName().toLowerCase().trim(), distanceFunction);
        }
        return builder.build();
    }

    public static DistanceFunction getDistanceFunction(String action) throws Exception {
        DistanceFunction distanceFunction;
        String[] tmp = action.split("\\|", 2);
        action = tmp[0].trim().toLowerCase();
        if (distanceFunctions.containsKey(action)) {
            distanceFunction = distanceFunctions.get(action).getClass().newInstance();
        } else {
            throw new Exception("Distance Function " + action + " was not found!");
        }
        if (tmp.length > 1) {
            distanceFunction.setParameters(tmp[1]);
        }
        return distanceFunction;
    }

}