Over-plotting validation and training data in the Mahalanobis ellipses

One of the great things of R is that we can get the code of the different functions (in this case the function "drawMahal" from the package "Chemometrics" ) and adapt this code to our necessities.

 

I wanted to over-plot the training set scores for the first and second principal components with the scores of the validation set, which are redundant samples taken apart in a selection process with the function "puchwain" from the package "prospectr", but I get problems with the scale due to the way "drawMahal" fix the X and Y limits. But editing the function we can create a personalize function for our case and to compare the redundant samples in red with the training samples in black.

 

Now the next is to over-plot the test samples (in theory bad samples) in another color in a coming post.