Projection Pursuit Classification Trees  May 14, 2013   I've
been looking at this article for a new tree-based method. It
uses other classification methods (e.g. LDA) to find a single
variable use in the split and builds a tree in that manner. The
subtleties of the model are:    • The model does not prune but
keeps splitting until achieving purity   • With more than two
classes, it treats the data as a two-class system in some parts
of the algorithm (but predictions are still based on the
original classes)  It is similar to oblique trees. These trees
look for linear combinations of predictors to use in a split.
The similarity between oblique trees and PPtree is the method of
finding splits. In each case, a more parametric model can be
used for this purpose. Some implementations of oblique trees use
PLS, L2 regularization or linear support vector machines to find
the optimal combination. Here, the authors use basic
discriminant functions but using only a single predictor at a
time. This connection wasn't menti