source: trunk/EventBenchCore/src/de/ugoe/cs/eventbench/coverage/CoverageCalculator.java @ 123

package de.ugoe.cs.eventbench.coverage;

import java.security.InvalidParameterException;
import java.util.Collection;
import java.util.List;
import java.util.Map;

import de.ugoe.cs.eventbench.data.Event;
import de.ugoe.cs.eventbench.models.IStochasticProcess;

/**
 * <p>
 * This class calculates various types of sequence coverage in relation to a
 * stochastic process.
 * </p>
 * 
 * @author Steffen Herbold
 * @version 1.0
 */
public class CoverageCalculator {

        /**
         * <p>
         * Stochastic process that is the foundation for probabilistic coverages and
         * coverages with reference to all possible sequences.
         * </p>
         */
        private final IStochasticProcess process;

        /**
         * <p>
         * Sequences for which the coverage is calculated.
         * </p>
         */
        private final Collection<List<? extends Event<?>>> sequences;

        /**
         * <p>
         * Length of the subsequences in relation to which the covarage is
         * calculated.
         * </p>
         */
        private final int length;

        /**
         * <p>
         * All subsequences of {@link #length} of {@link #sequences}.
         * </p>
         */
        private Collection<List<? extends Event<?>>> containedSubSeqs = null;

        /**
         * <p>
         * All subsequences of {@link #length} that can be generated by
         * {@link #process}.
         * </p>
         */
        private Collection<List<? extends Event<?>>> allPossibleSubSeqs = null;

        /**
         * <p>
         * The probabilities of al subsequences of {@link #length} according to
         * {@link #process}.
         * </p>
         */
        private Map<List<? extends Event<?>>, Double> subSeqWeights = null;

        /**
         * <p>
         * Constructor. Creates a new CoverageCalculator for a given stochastic
         * process and generated sequences.
         * </p>
         * 
         * @param process
         *            stochastic process used for coverage calculations; must not be
         *            null
         * @param sequences
         *            sequences for which the coverage is calculated; must not be
         *            null
         * @param length
         *            length of the subsequences for which the coverage is analyzed;
         *            must be >0
         */
        public CoverageCalculator(IStochasticProcess process,
                        Collection<List<? extends Event<?>>> sequences, int length) {
                if (process == null) {
                        throw new InvalidParameterException("process must not be null");
                }
                if (sequences == null) {
                        throw new InvalidParameterException("sequences must not be null");
                }
                if (length <= 0) {
                        throw new InvalidParameterException(
                                        "length must be >0; actual value: " + length);
                }
                this.process = process;
                this.sequences = sequences;
                this.length = length;
        }

        /**
         * <p>
         * Calculates the percentage of subsequences of length k that occur,
         * including those that cannot be generated by {@link #process}.
         * </p>
         * 
         * @return coverage percentage
         */
        public double getCoverageAllNoWeight() {
                if (containedSubSeqs == null) {
                        containedSubSeqs = SequenceTools.containedSubSequences(sequences,
                                        length);
                }
                return ((double) containedSubSeqs.size())
                                / SequenceTools.numSequences(process, length);
        }

        /**
         * <p>
         * Calculates the percentage of subsequences of length k that occur and can
         * generated by {@link #process}.
         * </p>
         * 
         * @return coverage percentage
         */
        public double getCoveragePossibleNoWeight() {
                if (containedSubSeqs == null) {
                        containedSubSeqs = SequenceTools.containedSubSequences(sequences,
                                        length);
                }
                if (allPossibleSubSeqs == null) {
                        allPossibleSubSeqs = process.generateSequences(length);
                }
                return ((double) containedSubSeqs.size()) / allPossibleSubSeqs.size();
        }

        /**
         * <p>
         * Calculates the weight of the subsequences that occur with relation to
         * {@link #process}, i.e., the mass of the subsequence probability covered
         * by the subsequences.
         * </p>
         * 
         * @return coverage weight
         */
        public double getCoveragePossibleWeight() {
                if (containedSubSeqs == null) {
                        containedSubSeqs = SequenceTools.containedSubSequences(sequences,
                                        length);
                }
                if (allPossibleSubSeqs == null) {
                        allPossibleSubSeqs = process.generateSequences(length);
                }
                if (subSeqWeights == null) {
                        subSeqWeights = SequenceTools.generateWeights(process,
                                        allPossibleSubSeqs);
                }
                double weight = 0.0;
                for (List<? extends Event<?>> subSeq : containedSubSeqs) {
                        weight += subSeqWeights.get(subSeq);
                }
                return weight;
        }

}