com.davidbracewell.math.distance.HammingDistance.java Source code

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Here is the source code for com.davidbracewell.math.distance.HammingDistance.java

Source

/*
 * (c) 2005 David B. Bracewell
 *
 * 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 com.davidbracewell.math.distance;

import com.google.common.base.Preconditions;
import com.google.common.collect.Sets;

import java.util.Map;

/**
 * @author David B. Bracewell
 */
public class HammingDistance extends DistanceMeasure {
    @Override
    public double calculate(Map<?, ? extends Number> m1, Map<?, ? extends Number> m2) {
        Preconditions.checkNotNull(m1, "Vectors cannot be null");
        Preconditions.checkNotNull(m2, "Vectors cannot be null");
        double sum = 0;
        for (Object o : Sets.union(m1.keySet(), m2.keySet())) {
            double d1 = m1.containsKey(o) ? m1.get(o).doubleValue() : 0d;
            double d2 = m2.containsKey(o) ? m2.get(o).doubleValue() : 0d;
            if (d1 != d2) {
                sum++;
            }
        }
        return sum;
    }

    @Override
    public double calculate(double[] v1, double[] v2) {
        Preconditions.checkNotNull(v1, "Vectors cannot be null");
        Preconditions.checkNotNull(v2, "Vectors cannot be null");
        Preconditions.checkArgument(v1.length == v2.length, "Dimension mismatch " + v1.length + " != " + v2.length);
        double sum = 0;
        for (int i = 0; i < v1.length; i++) {
            if (v1[i] != v2[i]) {
                sum++;
            }
        }
        return sum;
    }
}//END OF HammingDistance