Fixed mapping for selecting given features
[W,V] = FEATSEL(K,J)
This is a simple support routine that writes feature selection in terms of a mapping. If A is a K-dimensional dataset and J are the feature indices to be selected, then B = A*W does the same as B = A(:,J).
The use of this routine is a mapping V computed for a lower dimensional subspace defined by J can now be defined by W = FEATSEL(K,J)*V as a mapping in the original K-dimensional space.
The selected features can be retrieved by W.DATA or by +W. See below for various methods to perform feature selection.