Java 实现相似度算法

Java 实现相似度算法

通过JAVA编程，使用余弦定理，相似度算法的实现

/**
* 计算带有权重的相似度
* @param dict1：Map<String,Integer>：Map<特征词,权重值>
* @param dict2：Map<String,Integer>：Map<特征词,权重值>
* @return
*/
public double similarity(Map<String,Integer> dict1,Map<String,Integer> dict2){
double similarity = 0.0, numerator = 0.0, denominator1 = 0.0, denominator2 = 0.0;
if(dict1.size()==0||dict2.size()==0){
similarity = 0.0;
return similarity;
}
int value1=0;
int value2=0;
int num = 0;
for(String keyword:dict1.keySet()){
value1 = dict1.get(keyword);
if(dict2.containsKey(keyword)){
value2 = dict2.get(keyword);
dict2.remove(keyword);
num++;
}else{
value2 = 0;
}

numerator += value1 * value2; 
denominator1 += value1 * value1;
denominator2 += value2 * value2;
}

for(String keyword:dict2.keySet()){
value2 = dict2.get(keyword);
denominator2 += value2 * value2;
}
similarity = numerator / (Math.sqrt(denominator1 * denominator2)); 
return similarity;
}