/*
 * Copyright 2006 - 2013
 *     Stefan Balev     <stefan.balev@graphstream-project.org>
 *     Julien Baudry    <julien.baudry@graphstream-project.org>
 *     Antoine Dutot    <antoine.dutot@graphstream-project.org>
 *     Yoann Pigné      <yoann.pigne@graphstream-project.org>
 *     Guilhelm Savin   <guilhelm.savin@graphstream-project.org>
 * 
 * This file is part of GraphStream <http://graphstream-project.org>.
 * 
 * GraphStream is a library whose purpose is to handle static or dynamic
 * graph, create them from scratch, file or any source and display them.
 * 
 * This program is free software distributed under the terms of two licenses, the
 * CeCILL-C license that fits European law, and the GNU Lesser General Public
 * License. You can  use, modify and/ or redistribute the software under the terms
 * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
 * URL <http://www.cecill.info> or under the terms of the GNU LGPL 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * The fact that you are presently reading this means that you have had
 * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
 */
package org.graphstream.algorithm.measure;

import org.apache.commons.math.stat.descriptive.moment.*;

/**
 * Provides some statistical information on the size of current community
 * assignment on the specified graph as it evolves.
 * 
 * @author Guillaume-Jean Herbiet
 * 
 */
public class CommunityDistribution extends CommunityMeasure {

        /**
         * Biggest community currently generated.
         */
        protected Object biggestCommunity = null;

        /**
         * Smallest community currently generated.
         */
        protected Object smallestCommunity = null;

        /**
         * Average size of the currently generated communities.
         */
        protected float avgSize = 0;

        /**
         * Standard deviation of the size of currently generated communities.
         */
        protected float stdevSize = 0;

        /**
         * New size distribution measure using the specified marker as attribute
         * name for the community assignment.
         * 
         * @param marker
         *            Attribute name for the community assignment.
         */
        public CommunityDistribution(String marker) {
                super(marker);
        }

        @Override
        /**
         * Computes and update the statistical information on size distribution.
         * 
         * @complexity O(C), where C is the expected number of communities.
         */
        public void compute() {
                if (graphChanged) {
                        // Default measure is the number of communities
                        M = (float) communities.size();

                        // Update the smallest/biggest community
                        // and creates the size distribution
                        int maxSize = 0;
                        int minSize = Integer.MAX_VALUE;

                        double[] distribution = new double[(int) M];
                        int k = 0;
                        Mean mean = new Mean();
                        StandardDeviation stdev = new StandardDeviation();

                        for (Object c : communities.keySet()) {
                                distribution[k++] = (communities.get(c)).size();

                                if ((communities.get(c)).size() > maxSize) {
                                        biggestCommunity = c;
                                        maxSize = (communities.get(c)).size();
                                }
                                if ((communities.get(c)).size() < minSize) {
                                        smallestCommunity = c;
                                        minSize = (communities.get(c)).size();
                                }
                        }

                        // Compute the statistical moments
                        avgSize = (float) mean.evaluate(distribution);
                        stdevSize = (float) stdev.evaluate(distribution);

                        graphChanged = false;
                }
        }

        /**
         * Get the number of communities
         * 
         * @return an int representing the current number of communities
         */
        public int number() {
                return (int) M;
        }

        /**
         * Get the biggest generated community
         * 
         * @return the biggest community
         */
        public Object biggestCommunity() {
                return biggestCommunity;
        }

        /**
         * Get the smallest generated community
         * 
         * @return the smallest community
         */
        public Object smallestCommunity() {
                return smallestCommunity;
        }

        /**
         * Get the maximum community size
         * 
         * @return an int reflecting the size of the biggest community
         */
        public int maxCommunitySize() {
                if (communities.get(biggestCommunity) == null)
                        return 0;
                else
                        return (communities.get(biggestCommunity)).size();
        }

        /**
         * Get the minimum community size
         * 
         * @return an int reflecting the size of the smallest community
         */
        public int minCommunitySize() {
                if (communities.get(smallestCommunity) == null)
                        return 0;
                else
                        return (communities.get(smallestCommunity)).size();
        }

        /**
         * Compute the average community size
         * 
         * @return Average community size
         */
        public float average() {
                return avgSize;
        }

        /**
         * Compute the standard deviation of the community size
         * 
         * @return Standard deviation of the community size
         */
        public float stdev() {
                return stdevSize;
        }

        /**
         * Updates the distribution information and returns a string for an easy
         * display of the results.
         * 
         * The string has the following format: [number of communities] [average
         * size] [stdev size] [min size] ([smallest community]) [max size] ([biggest
         * community])
         * 
         * @return a String containing all computed distribution information.
         */
        @Override
        public String toString() {
                compute();
                return (int) M + " " + avgSize + " " + stdevSize + " "
                                + minCommunitySize() + " (" + smallestCommunity + ") "
                                + maxCommunitySize() + " (" + biggestCommunity + ")";
        }

}