Code for categorical features is broken/incomplete

[joby-h20]

I believe that code for _first_order_ale_cat is broken or incomplete.

[MaximeJumelle]

Hello,

Indeed the function _first_order_ale_cat is not providing the expected output. It is due to the fact that sorting categorical feature is a bit more complicated than with numerical features.
It is suggested to use a dimensionality reduction algorithm such as MDS to provide a one-dimensional array with numerical features to easily sort it.