`xval` has been set to `0` by default for speed.

Argument of: rpart::rpart.control

the minimum number of observations that must exist in a node in order for a split to be attempted.

Argument of: rpart::rpart.control

the minimum number of observations in any terminal <leaf> node. If only one of minbucket or minsplit is specified, the code either sets minsplit to minbucket*3 or minbucket to minsplit/3, as appropriate.

Argument of: rpart::rpart.control

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.

Argument of: rpart::rpart.control

the number of competitor splits retained in the output.  It is useful to know not just which split was chosen, but which variable came in second, third, etc.

Argument of: rpart::rpart.control

the number of surrogate splits retained in the output.  If this is set to zero the compute time will be reduced, since approximately half of the computational time (other than setup) is used in the search for surrogate splits.

Argument of: rpart::rpart.control

how to use surrogates in the splitting process.  0 means display only; an observation with a missing value for the primary split rule is not sent further down the tree.  1 means use surrogates, in order, to split subjects missing the primary variable; if all surrogates are missing the observation is not split.  For value 2 ,if all surrogates are missing, then send the observation in the majority direction.  A value of 0 corresponds to the action of tree, and 2 to the recommendations of Breiman et.al (1984).

Argument of: rpart::rpart.control

number of cross-validations.