com.cloudera.oryx.kmeans.computation.covariance.CoMomentTracker.java Source code

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Here is the source code for com.cloudera.oryx.kmeans.computation.covariance.CoMomentTracker.java

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/**
 * Copyright (c) 2013, Cloudera, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. 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
 *
 * This software 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 com.cloudera.oryx.kmeans.computation.covariance;

import com.google.common.collect.Maps;
import org.apache.commons.math3.linear.RealVector;

import java.util.Map;
import java.util.Set;

final class CoMomentTracker {
    private final Map<Index, CoMoment> cache = Maps.newHashMap();

    public void reset() {
        cache.clear();
    }

    public void update(RealVector v) {
        for (int i = 0; i < v.getDimension(); i++) {
            double vi = v.getEntry(i);
            for (int j = i; j < v.getDimension(); j++) {
                Index idx = new Index(i, j);
                CoMoment cm = cache.get(idx);
                if (cm == null) {
                    cm = new CoMoment();
                    cache.put(idx, cm);
                }
                cm.update(vi, v.getEntry(j));
            }
        }
    }

    public Set<Map.Entry<Index, CoMoment>> entrySet() {
        return cache.entrySet();
    }
}