plotcp {rpart} | R Documentation

## Plot a Complexity Parameter Table for an Rpart Fit

### Description

Gives a visual representation of the cross-validation results in an `rpart` object.

### Usage

    plotcp(x, minline = TRUE, lty = 3, col = 1,
           upper = c("size", "splits", "none"), ...)

### Arguments

`x` | an object of class `rpart`
`minline` | whether a horizontal line is drawn 1SE above the minimum of the curve.
`lty` | line type for this line
`col` | colour for this line
`upper` | what is plotted on the top axis: the size of the tree (the number of leaves), the number of splits or nothing.
`...` | additional plotting parameters

### Details

The set of possible cost-complexity prunings of a tree from a nested set. For the geometric means of the intervals of values of `cp` for which a pruning is optimal, a cross-validation has (usually) been done in the initial construction by `rpart`. The `cptable` in the fit contains the mean and standard deviation of the errors in the cross-validated prediction against each of the geometric means, and these are plotted by this function. A good choice of `cp` for pruning is often the leftmost value for which the mean lies below the horizontal line.

### Value

None.

### Side Effects

A plot is produced on the current graphical device.

### See Also

`rpart`, `printcp`, `rpart.object`

[Package rpart version 3.1-23 Index]