Drop categorical variables with higher number of levels
max_target_cat
Maximum number of categories to be plotted for target (except NA)
maxdepth
Set the maximum depth of any node of the final tree, with the root
node counted as depth 0. Values greater than 30 rpart will
give nonsense results on 32-bit machines.
minsplit
the minimum number of observations that must exist in a node in order for
a split to be attempted.
cp
complexity parameter. Any split that does not decrease the overall
lack of fit by a factor of cp is not attempted. For instance,
with anova splitting, this means that the overall R-squared must
increase by cp at each step. The main role of this parameter
is to save computing time by pruning off splits that are obviously
not worthwhile. Essentially,the user informs the program that any
split which does not improve the fit by cp will likely be
pruned off by cross-validation, and that hence the program need
not pursue it.