用java实现皮尔逊（Pearson）相关系数计算
package success;
import java.util.List;
/**
* 皮尔逊相关系数
*/
public class PearsonDemo {
public static void main(String[] args) {
test();
}
private static void test(){
/*用于测试*/
double[] x = new double[] { 38 ,13 ,27, 25, 18, 29, 30, 20, 23, 32, 38, 28, 34, 19, 20, 25, 16, 36, 25, 17, 24, 18, 30, 35, 22, 34, 12, 26, 29, 21};
//double[] y = new double[] { 49 ,42, 45, 39, 30, 25, 39, 36, 39 ,45, 42, 50, 36, 48, 35, 42, 45, 29, 33, 27, 42, 43, 27, 39, 37, 36, 47, 37, 44, 34};
double[] y = new double[] {114, 49, 84, 79, 87, 74, 77, 82, 80, 88, 123, 82, 98, 65, 61, 78, 51, 121, 78, 50, 75, 65, 113, 122, 78, 119, 45, 89, 102, 75};
double score = getPearsonCorrelationScore(x, y);
System.out.println(score);//0.6350393282549671
}
public static double getPearsonCorrelationScore(List<Double> x, List<Double> y) {
if (x.size() != y.size())
throw new RuntimeException("数据不正确！");
double[] xData = new double[x.size()];
double[] yData = new double[x.size()];
for (int i = 0; i < x.size(); i++) {
xData[i] = x.get(i);
yData[i] = y.get(i);
}
return getPearsonCorrelationScore(xData,yData);
}
public static double getPearsonCorrelationScore(double[] xData, double[] yData) {
if (xData.length != yData.length)
throw new RuntimeException("数据不正确！");
double xMeans;
double yMeans;
double numerator = 0;// 求解皮尔逊的分子
double denominator = 0;// 求解皮尔逊系数的分母
double result = 0;
// 拿到两个数据的平均值
xMeans = getMeans(xData);
yMeans = getMeans(yData);
// 计算皮尔逊系数的分子
numerator = generateNumerator(xData, xMeans, yData, yMeans);
// 计算皮尔逊系数的分母
denominator = generateDenomiator(xData, xMeans, yData, yMeans);
// 计算皮尔逊系数
result = numerator / denominator;
return result;
}
/**
* 计算分子
*
* @param xData
* @param xMeans
* @param yData
* @param yMeans
* @return
*/
private static double generateNumerator(double[] xData, double xMeans, double[] yData, double yMeans) {
double numerator = 0.0;
for (int i = 0; i < xData.length; i++) {
numerator += (xData[i] - xMeans) * (yData[i] - yMeans);
}
return numerator;
}
/**
* 生成分母
*
* @param yMeans
* @param yData
* @param xMeans
* @param xData
* @return 分母
*/
private static double generateDenomiator(double[] xData, double xMeans, double[] yData, double yMeans) {
double xSum = 0.0;
for (int i = 0; i < xData.length; i++) {
xSum += (xData[i] - xMeans) * (xData[i] - xMeans);
}
double ySum = 0.0;
for (int i = 0; i < yData.length; i++) {
ySum += (yData[i] - yMeans) * (yData[i] - yMeans);
}
return Math.sqrt(xSum) * Math.sqrt(ySum);
}
/**
* 根据给定的数据集进行平均值计算
*
* @param
* @return 给定数据集的平均值
*/
private static double getMeans(double[] datas) {
double sum = 0.0;
for (int i = 0; i < datas.length; i++) {
sum += datas[i];
}
return sum / datas.length;
}
}
