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Calculate The Pearson's Correlation In JAVA
// calculate the Pearson's correlation in JAVA
public class Correlation {
public static double getPearsonCorrelation(double[] scores1,double[] scores2){
double result = 0;
double sum_sq_x = 0;
double sum_sq_y = 0;
double sum_coproduct = 0;
double mean_x = scores1[0];
double mean_y = scores2[0];
for(int i=2;i<scores1.length+1;i+=1){
double sweep =Double.valueOf(i-1)/i;
double delta_x = scores1[i-1]-mean_x;
double delta_y = scores2[i-1]-mean_y;
sum_sq_x += delta_x * delta_x * sweep;
sum_sq_y += delta_y * delta_y * sweep;
sum_coproduct += delta_x * delta_y * sweep;
mean_x += delta_x / i;
mean_y += delta_y / i;
}
double pop_sd_x = (double) Math.sqrt(sum_sq_x/scores1.length);
double pop_sd_y = (double) Math.sqrt(sum_sq_y/scores1.length);
double cov_x_y = sum_coproduct / scores1.length;
result = cov_x_y / (pop_sd_x*pop_sd_y);
return result;
}
}
