VertexFrame covariance

---

covariance(self, data_column_names)

Calculate covariance for exactly two columns.

Parameters:

data_column_names : list

The names of two columns from which to compute the covariance.

Returns:

: float64

Covariance of the two columns.

This method applies only to columns containing numerical data.

Examples

Consider Frame my_frame, which contains the data

>>> my_frame.inspect()
[#]  idnum  x1   x2   x3   x4
===============================
[0]      0  1.0  4.0  0.0  -1.0
[1]      1  2.0  3.0  0.0  -1.0
[2]      2  3.0  2.0  1.0  -1.0
[3]      3  4.0  1.0  2.0  -1.0
[4]      4  5.0  0.0  2.0  -1.0

my_frame.covariance computes the covariance on the pair of columns provided.

>>> my_frame.covariance(["x1", "x2"])
[===Job Progress===]

-2.5

>>> my_frame.covariance(["x1", "x4"])
[===Job Progress===]

0.0

>>> my_frame.covariance(["x2", "x3"])
[===Job Progress===]

-1.5