R: Plot an Rpart Object

plot.rpart {rpart}

R Documentation

Plot an Rpart Object

Description

Plots an rpart object on the current graphics device.

Usage

## S3 method for class 'rpart'
plot(x, uniform = FALSE, branch = 1, compress = FALSE, nspace,
     margin = 0, minbranch = 0.3, ...)

Arguments

`x`	a fitted object of class `"rpart"`, containing a classification, regression, or rate tree.
`uniform`	if `TRUE`, uniform vertical spacing of the nodes is used; this may be less cluttered when fitting a large plot onto a page. The default is to use a non-uniform spacing proportional to the error in the fit.
`branch`	controls the shape of the branches from parent to child node. Any number from 0 to 1 is allowed. A value of 1 gives square shouldered branches, a value of 0 give V shaped branches, with other values being intermediate.
`compress`	if `FALSE`, the leaf nodes will be at the horizontal plot coordinates of `1:nleaves`. If `TRUE`, the routine attempts a more compact arrangement of the tree. The compaction algorithm assumes `uniform=TRUE`; surprisingly, the result is usually an improvement even when that is not the case.
`nspace`	the amount of extra space between a node with children and a leaf, as compared to the minimal space between leaves. Applies to compressed trees only. The default is the value of `branch`.
`margin`	an extra fraction of white space to leave around the borders of the tree. (Long labels sometimes get cut off by the default computation).
`minbranch`	set the minimum length for a branch to `minbranch` times the average branch length. This parameter is ignored if `uniform=TRUE`. Sometimes a split will give very little improvement, or even (in the classification case) no improvement at all. A tree with branch lengths strictly proportional to improvement leaves no room to squeeze in node labels.
`...`	arguments to be passed to or from other methods.

Details

This function is a method for the generic function plot, for objects of class rpart. The y-coordinate of the top node of the tree will always be 1.

Value

The coordinates of the nodes are returned as a list, with components x and y.

Side Effects

An unlabeled plot is produced on the current graphics device: one being opened if needed.

In order to build up a plot in the usual S style, e.g., a separate text command for adding labels, some extra information about the plot needs be retained. This is kept in an environment in the package.

Examples

fit <- rpart(Price ~ Mileage + Type + Country, cu.summary)
par(xpd = TRUE)
plot(fit, compress = TRUE)
text(fit, use.n = TRUE)

[Package rpart version 4.1-12 Index]