java 如何在java中找到两个整数数组之间的相关性
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How to find correlation between two integer arrays in java
提问by Surjya Narayana Padhi
I am searching a lot but could not find exactly what i need till now.
I have two integer arrayas int[] xand int[] y. I want to find simple linear correlationbetween these two integer arrays and it should return the result as double. In java do you know any library function providing this or any code snippet?
我搜索了很多，但直到现在都找不到我需要的东西。我有两个整数数组int[] x和int[] y. 我想在这两个整数数组之间找到简单的线性相关性，它应该将结果返回为double. 在 Java 中，您知道提供此或任何代码片段的任何库函数吗？
回答by Dmitry Bychenko
Correlation is quite easy to computemanually:
相关性很容易手动计算：
http://en.wikipedia.org/wiki/Correlation_and_dependence
http://en.wikipedia.org/wiki/Correlation_and_dependence
public static double Correlation(int[] xs, int[] ys) {
//TODO: check here that arrays are not null, of the same length etc
double sx = 0.0;
double sy = 0.0;
double sxx = 0.0;
double syy = 0.0;
double sxy = 0.0;
int n = xs.length;
for(int i = 0; i < n; ++i) {
double x = xs[i];
double y = ys[i];
sx += x;
sy += y;
sxx += x * x;
syy += y * y;
sxy += x * y;
}
// covariation
double cov = sxy / n - sx * sy / n / n;
// standard error of x
double sigmax = Math.sqrt(sxx / n - sx * sx / n / n);
// standard error of y
double sigmay = Math.sqrt(syy / n - sy * sy / n / n);
// correlation is just a normalized covariation
return cov / sigmax / sigmay;
}
回答by Hamed Moghaddam
There is nothing in core Java. There are libraries out there you can use. Apache Commons has a statistical project, check PearsonCorrelationclass.
核心 Java 中没有任何内容。您可以使用一些库。Apache Commons 有一个统计项目，查看PearsonCorrelation类。
Sample code:
示例代码：
public static void main(String[] args) {
double[] x = {1, 2, 4, 8};
double[] y = {2, 4, 8, 16};
double corr = new PearsonsCorrelation().correlation(y, x);
System.out.println(corr);
}
prints out 1.0
打印出 1.0
