meanvar.rpart {rpart}  R Documentation 
Creates a plot on the current graphics device of the deviance of the node divided by the number of observations at the node. Also returns the node number.
meanvar(tree, ...) ## S3 method for class 'rpart': meanvar(tree, xlab="ave(y)", ylab="ave(deviance)", ...)
tree 
fitted model object of class rpart . This is asumed to be the result
of some function that produces an object with the same named
components as that returned by the rpart function.

xlab 
xaxis label for the plot. 
ylab 
yaxis label for the plot. 
... 
additional graphical parameters may be supplied as arguments to this function. 
an invisible list containing the following vectors is returned.
x 
fitted value at terminal nodes (yval ).

y 
deviance of node divided by number of observations at node. 
label 
node number. 
a plot is put on the current graphics device.
z.auto < rpart(Mileage ~ Weight, car.test.frame) meanvar(z.auto, log='xy')