Feature: Add loadings scale on secondary axes

[Rendiere]

When visualising bi-plots, it's often useful to interpret the loadings placed on each feature in order to make deductions such as "principle component 1 places approximately double the loading on features A,B & C than it places on feature D".

Without the scale of the loading vectors in each principle component direction explicitly known however, this can lead to misleading deductions.

This feature request is thus to add the loading scales to each principle component axis.

Example of biplot with loading scales shown:

[erdogant]

I agree and added the loading information to the plot. update with:

pip install -U pca The new version should be >= 1.0.8

import pca
print(pca.__version__)