split rule 1:mean of two group means, 2:weighted mean, 3: mean of max(left group) and min(right group), 4: weighted mean of max(left group) and min(right group)
true.class
true class of test dataset if available
References
Lee, YD, Cook, D., Park JW, and Lee, EK(2013)
PPtree: Projection pursuit classification tree,
Electronic Journal of Statistics, 7:1369-1386.