R help - Jun 2004 - Error when I try to build / plot a tree using rpart()

Hi,

I am using the rpart package to build a classification tree. I did 
manage to build a tree with data on a previous project. However, when 
attampting to build a tree on a project I am working on, I seem to be 
getting the error shown below:

 > nhg3.rp <- rpart(profitresp ~., nhg3, method="class")
 > plot(nhg3.rp, branch=0.4, uniform=T); text(nhg3.rp, digits=3)
Error in yval[, 1] : incorrect number of dimensions

The distribution of my binary dependent variable is:
 > table(nhg$profitresp)

   0    1
3703 4360

I am using 105 potential predictor variables. I am trying to come up 
with a decision rule to identify profitable responders from 
non-responders to a mailing.

Some other details are:
 > summary(nhg3.rp)
Call:
rpart(formula = profitresp ~ ., data = nhg3, method = "class")
  n= 8063

           CP nsplit rel error
1 0.009451796      0         1
Error in yval[, 1] : incorrect number of dimensions

 > print(nhg3.rp)
n= 8063

node), split, n, loss, yval, (yprob)
      * denotes terminal node

1) root 8063 3703 1 (0.4592583 0.5407417) *

 > printcp(nhg3.rp)

Classification tree:
rpart(formula = profitresp ~ ., data = nhg3, method = "class")

Variables actually used in tree construction:
character(0)

Root node error: 3703/8063 = 0.45926

n= 8063

         CP nsplit rel error
1 0.0094518      0         1

Any help is appreciated.

Thanks much,

Jude Ryan

You didn't get a tree.  The output of print() tells you that you only have
the root node.  You may need to adjust some of the parameters with
rpart(..., control=rpart.control(...)).  See ?rpart.control.

HTH,
Andy
> From: Jude Ryan
> 
> Hi,
> 
> I am using the rpart package to build a classification tree. I did 
> manage to build a tree with data on a previous project. However, when 
> attampting to build a tree on a project I am working on, I seem to be 
> getting the error shown below:
> 
>  > nhg3.rp <- rpart(profitresp ~., nhg3, method="class")
>  > plot(nhg3.rp, branch=0.4, uniform=T); text(nhg3.rp, digits=3)
> Error in yval[, 1] : incorrect number of dimensions
> 
> The distribution of my binary dependent variable is:
>  > table(nhg$profitresp)
> 
>    0    1
> 3703 4360
> 
> I am using 105 potential predictor variables. I am trying to come up 
> with a decision rule to identify profitable responders from 
> non-responders to a mailing.
> 
> Some other details are:
>  > summary(nhg3.rp)
> Call:
> rpart(formula = profitresp ~ ., data = nhg3, method = "class")
>   n= 8063
> 
>            CP nsplit rel error
> 1 0.009451796      0         1
> Error in yval[, 1] : incorrect number of dimensions
> 
>  > print(nhg3.rp)
> n= 8063
> 
> node), split, n, loss, yval, (yprob)
>       * denotes terminal node
> 
> 1) root 8063 3703 1 (0.4592583 0.5407417) *
> 
>  > printcp(nhg3.rp)
> 
> Classification tree:
> rpart(formula = profitresp ~ ., data = nhg3, method = "class")
> 
> Variables actually used in tree construction:
> character(0)
> 
> Root node error: 3703/8063 = 0.45926
> 
> n= 8063
> 
>          CP nsplit rel error
> 1 0.0094518      0         1
> 
> Any help is appreciated.
> 
> Thanks much,
> 
> Jude Ryan
> 
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