R help - Jan 2008 - rpart error when constructing a classification tree

I am trying to make a decision tree using rpart. The function runs very
quickly considering the size of the data (1742, 163). When I call the
summary command I get this:
> summary(bookings.cart)
Call:
rpart(formula = totalRev ~ ., data = bookings, method = "class")
  n=1741 (1 observation deleted due to missingness)

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


note:
> dim(bookings)
[1] 1742  163


I have run rpart on past projects without any problems. I have used a
catagorical version of the variable totalRev that was partitioned into four
levels (and coded as a factor).
I tried making a tree with the tree command (in the 'tree' package) and
was
able to construct a tree without any errors. However, I would much rather
use rpart.

Does anyone have any ideas that might help?

	[[alternative HTML version deleted]]

Randy Griffiths wrote:
> I am trying to make a decision tree using rpart. The function runs very
> quickly considering the size of the data (1742, 163). When I call the
> summary command I get this:
> 
>> summary(bookings.cart)
> Call:
> rpart(formula = totalRev ~ ., data = bookings, method = "class")
>   n=1741 (1 observation deleted due to missingness)
> 
>   CP nsplit rel error
> 1  0      0         1
> Error in yval[, 1] : incorrect number of dimensions
> 

And we get:

R> summary(bookings.cart)
Error in summary(bookings.cart) : object "bookings.cart" not found

hence we cannot reproduce and inspect your problem. Please read the 
posting guide.

Uwe Ligges

> note:
>> dim(bookings)
> [1] 1742  163
> 
> 
> I have run rpart on past projects without any problems. I have used a
> catagorical version of the variable totalRev that was partitioned into four
> levels (and coded as a factor).
> I tried making a tree with the tree command (in the 'tree' package)
and was
> able to construct a tree without any errors. However, I would much rather
> use rpart.
> 
> Does anyone have any ideas that might help?
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

I am trying to make a decision tree using rpart. This is my code and
output.
> data <- read.table("/Users/randygriffiths/Desktop/data",
header=T)
> attach(data)
>
> library(rpart)
> bookings.cart <- rpart(totalRev~., data=data, method="class")
> bookings.cart
n= 50

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

1) root 50 15 0 (0.7 0.04 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02
0.02 0.02 0.02) *
> summary(bookings.cart)
Call:
rpart(formula = totalRev ~ ., data = data, method = "class")
  n= 50

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


I have used rpart on past projects without any problems. I can do a
regression tree without any error as well (by leaving off the
method="class"
argument). I have used this same data using 'randomForest' with good
results
and also using 'tree' without this error. I have seen that at least a
few
people have reported getting this same error with rpart, but I could not
find an answer that helped the problem. Can anyone help me?

Randy