[R] Decision trees with factors and numericals

[David Winsemius]

On Nov 24, 2009, at 8:50 AM, Joel Fürstenberg-Hägg wrote:
>
> Does any of you know how to make a decision tree when the data set  
> contains factors and numericals?
>
> I've got a data frame with 3 columns, where y and x1 are numerical  
> and x2 contains factors. Is it possible to use the rpart package,  
> and in that case how? Otherwise, is there another alternative?
>
> This is what I've tried so far
>
>> rpart(LT50_NA ~ Raf + Antho, data=decTreeNA, method=anova) # Have  
>> tried "method=class" as well
> Error in as.character(x) :
>  cannot coerce type 'closure' to vector of type 'character'
>

I do not think that error is arising because you have a factor on the  
RHS of the equation. It would have been extremely surprising to find  
that rpart would be complaining about encountering a factor. I think  
it is because you failed to enclose anova with quotes. The message is  
telling you that R encountered a function (a closure)  where it was  
"hoping for"  a character variable.

>
-- 

David Winsemius, MD
Heritage Laboratories
West Hartford, CT