snip.rpart: Snip Subtrees of an Rpart Object

Description

Creates a "snipped" rpart object, containing the nodes that remain after selected subtrees have been snipped off. The user can snip nodes using the toss argument, or interactively by clicking the mouse button on specified nodes within the graphics window.

Usage

snip.rpart(x, toss)

Arguments

fitted model object of class "rpart". This is assumed to be the result of some function that produces an object with the same named components as that returned by the rpart function.

toss

an integer vector containing indices (node numbers) of all subtrees to be snipped off. If missing, user selects branches to snip off as described below.

Value

A rpart object containing the nodes that remain after specified or selected subtrees have been snipped off.

Warning

Visually erasing the plot is done by over-plotting with the background colour. This will do nothing if the background is transparent (often true for screen devices).

Details

A dendrogram of rpart is expected to be visible on the graphics device, and a graphics input device (e.g., a mouse) is required. Clicking (the selection button) on a node displays the node number, sample size, response y-value, and Error (dev). Clicking a second time on the same node snips that subtree off and visually erases the subtree. This process may be repeated an number of times. Warnings result from selecting the root or leaf nodes. Clicking the exit button will stop the snipping process and return the resulting rpart object.

See the documentation for the specific graphics device for details on graphical input techniques.

Examples

Run this code

# NOT RUN {
## dataset not in R
# }
# NOT RUN {
z.survey <- rpart(market.survey) # grow the rpart object
plot(z.survey) # plot the tree
z.survey2 <- snip.rpart(z.survey, toss = 2) # trim subtree at node 2
plot(z.survey2) # plot new tree

# can also interactively select the node using the mouse in the
# graphics window
# }

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