Creates a "snipped"
itree 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. Same as
fitted model object of class
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.
A dendrogram of
itree 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
See the documentation for the specific graphics device for details on graphical input techniques.
itree object containing the nodes that remain after specified or
selected subtrees have been snipped off.
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).
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## dataset not in R ## same as rpart: ## Not run: z.survey <- itree(market.survey) #grow the itree object plot(z.survey) #plot the tree z.survey2 <- snip.itree(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 ## End(Not run) #works with itree fits as well: z.auto <- itree(Mileage ~ Weight, method="purity",car.test.frame) #snip off the long branch: z.auto2 <- snip.itree(z.auto,toss=3)