Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;

import java.util.Map;
import java.util.Map.Entry;

public class Main {
    /**
     * Cosine similarity
     * 
     * @param map1
     * @param map2
     * @return sim(map1, map2) = dotProduct / (map1Magnitude * map2Magnitude);
     */
    public static Double calculateCosine(Map<Object, Integer> map1, Map<Object, Integer> map2) {
        Integer dotProduct = calculateDotProduct(map1, map2);
        Double map1Magnitude = calculateMagnitude(map1);
        Double map2Magnitude = calculateMagnitude(map2);
        Double coefficient = dotProduct / (map1Magnitude * map2Magnitude);
        return coefficient;

    }

    private static Integer calculateDotProduct(Map<Object, Integer> map1, Map<Object, Integer> map2) {
        Integer sum = 0;
        for (Entry<Object, Integer> entry1 : map1.entrySet()) {
            Integer value1 = entry1.getValue();
            Integer value2 = map2.get(entry1.getKey());
            if (value2 != null) {
                Integer prod = value1 * value2;
                sum += prod;
            }
        }
        return sum;
    }

    private static Double calculateMagnitude(Map<Object, Integer> map1) {
        Double sum = 0.0;
        for (Integer value : map1.values()) {
            sum += Math.pow(value, 2);
        }

        return Math.sqrt(sum);
    }

    public static Number getValue(Map<? extends Object, ? extends Number> map, Object key, Class<?> clazz) {
        Number value = map.get(key);
        if (value == null) {
            if (clazz.equals(Double.class)) {
                value = 0.0;
            } else {
                value = 0;
            }
        }
        return value;
    }
}