Plot a Complexity Parameter Table for an Arbor Fit

DESCRIPTION:

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

USAGE:

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

REQUIRED ARGUMENTS:

x
an object of class arbor

OPTIONAL ARGUMENTS:

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

VALUE:

None.

SIDE EFFECTS:

A plot is produced on the current graphical device.

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 arbor. 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.

SEE ALSO:

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