meanvar.rpart             package:rpart             R Documentation

Mean-Variance Plot for an Rpart Object

Description:

     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.

Usage:

     meanvar(tree, ...)

     ## S3 method for class 'rpart':
     meanvar(tree, xlab="ave(y)", ylab="ave(deviance)", ...)

Arguments:

    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: x-axis label for the plot.  

    ylab: y-axis label for the plot.  

     ...: additional graphical parameters may be supplied as arguments
          to this function.  

Value:

     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.  

Side Effects:

     a plot is put on the current graphics device.

See Also:

     'plot.rpart'.

Examples:

     data(car.test.frame)
     z.auto <- rpart(Mileage ~ Weight, car.test.frame)
     meanvar(z.auto, log='xy')

