org.apache.mahout.clustering.kmeans.Kluster.java Source code

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Here is the source code for org.apache.mahout.clustering.kmeans.Kluster.java

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/* Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.mahout.clustering.kmeans;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.mahout.clustering.iterator.DistanceMeasureCluster;
import org.apache.mahout.common.distance.DistanceMeasure;
import org.apache.mahout.math.Vector;

public class Kluster extends DistanceMeasureCluster {

    /** Has the centroid converged with the center? */
    private boolean converged;

    /** For (de)serialization as a Writable */
    public Kluster() {
    }

    /**
     * Construct a new cluster with the given point as its center
     * 
     * @param center
     *          the Vector center
     * @param clusterId
     *          the int cluster id
     * @param measure
     *          a DistanceMeasure
     */
    public Kluster(Vector center, int clusterId, DistanceMeasure measure) {
        super(center, clusterId, measure);
    }

    /**
     * Format the cluster for output
     * 
     * @param cluster
     *          the Cluster
     * @return the String representation of the Cluster
     */
    public static String formatCluster(Kluster cluster) {
        return cluster.getIdentifier() + ": " + cluster.computeCentroid().asFormatString();
    }

    public String asFormatString() {
        return formatCluster(this);
    }

    @Override
    public void write(DataOutput out) throws IOException {
        super.write(out);
        out.writeBoolean(converged);
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        super.readFields(in);
        this.converged = in.readBoolean();
    }

    @Override
    public String toString() {
        return asFormatString(null);
    }

    @Override
    public String getIdentifier() {
        return (converged ? "VL-" : "CL-") + getId();
    }

    /**
     * Return if the cluster is converged by comparing its center and centroid.
     * 
     * @param measure
     *          The distance measure to use for cluster-point comparisons.
     * @param convergenceDelta
     *          the convergence delta to use for stopping.
     * @return if the cluster is converged
     */
    public boolean computeConvergence(DistanceMeasure measure, double convergenceDelta) {
        Vector centroid = computeCentroid();
        converged = measure.distance(centroid.getLengthSquared(), centroid, getCenter()) <= convergenceDelta;
        return converged;
    }

    @Override
    public boolean isConverged() {
        return converged;
    }

    protected void setConverged(boolean converged) {
        this.converged = converged;
    }

    public boolean calculateConvergence(double convergenceDelta) {
        Vector centroid = computeCentroid();
        converged = getMeasure().distance(centroid.getLengthSquared(), centroid, getCenter()) <= convergenceDelta;
        return converged;
    }

}