相关系数

皮尔逊积矩相关系数,又称“相关系数”，

取值范围为[-1,1]，r=0，没有相关性。

-1：表示方向完全相反

1：表示方向相同，并且完全一样

0：表示没有相关性

函数签名：

numpy.corrcoef(x, y=None, rowvar=True, bias=<no value>, ddof=<no value>)

rowvar：True，表示每行代表一个变量，列中包含观测值。否则，关系将被转置：每列表示一个变量，而行包含观测值。

参考：

https://www.osgeo.cn/numpy/reference/generated/numpy.corrcoef.html # 中文说明文档

https://numpy.org/doc/stable/reference/generated/numpy.corrcoef.html  # 英文说明文档

内容如下：

numpy.corrcoef
numpy.corrcoef(x, y=None, rowvar=True, bias=<no value>, ddof=<no value>)[source]
Return Pearson product-moment correlation coefficients.

Please refer to the documentation for cov for more detail. The relationship between the correlation coefficient matrix, R, and the covariance matrix, C, is

R_{ij} = { C_{ij} } / { sqrt{ C_{ii} * C_{jj} } }

Parameters
xarray_like
A 1-D or 2-D array containing multiple variables and observations. Each row of x represents a variable, and each column a single observation of all those variables. Also see rowvar below.

yarray_like, optional
An additional set of variables and observations. y has the same shape as x.

rowvarbool, optional
If rowvar is True (default), then each row represents a variable, with observations in the columns. Otherwise, the relationship is transposed: each column represents a variable, while the rows contain observations.

bias_NoValue, optional
Has no effect, do not use.

Deprecated since version 1.10.0.

ddof_NoValue, optional
Has no effect, do not use.

Deprecated since version 1.10.0.

Returns
Rndarray
The correlation coefficient matrix of the variables.