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

Introduction

Here is the source code for com.davidbracewell.math.distance.EuclideanDistance.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;
import java.util.Set;

/**
 * @author David B. Bracewell
 */
public class EuclideanDistance 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 diff = 0d;
        Set<?> union = Sets.union(m1.keySet(), m2.keySet());
        for (Object key : union) {
            if (!m1.containsKey(key)) {
                diff += Math.pow(m2.get(key).doubleValue(), 2);
            } else if (!m2.containsKey(key)) {
                diff += Math.pow(m1.get(key).doubleValue(), 2);
            } else {
                diff += Math.pow(m1.get(key).doubleValue() - m2.get(key).doubleValue(), 2);
            }
        }
        return Math.sqrt(diff);
    }

    @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, "Vector dimension mismatch");
        double distance = 0d;
        for (int i = 0; i < v1.length; i++) {
            distance += Math.pow(v1[i] - v2[i], 2);
        }
        return Math.sqrt(distance);
    }

}//END OF EuclideanDistance