[R] Puzzled at rpart prediction

[Uwe Ligges]

Ajay Narottam Shah wrote:

> I'm in a situation where I say:
> 
> 
>>predict(m.rpart, newdata=D[N1+t,])
> 
>       0   1
> 173 0.8 0.2
> 
> which I interpret as meaning: an 80% chance of "0" and a 20% chance of
> "1". Okay. This is consistent with:
> 
> 
>>predict(m.rpart, newdata=D[N1+t,], type="class")
> 
> [1] 0
> Levels: 0 1
> 
> But I'm puzzled at the following. If I say:
> 
> 
>>predict(m.rpart, newdata=D[N1+t,], type="vector")
> 
> 173 
>   1 
> 
> What gives?

This means that the class of the first level is chosen, and the first 
level is "0".

Uwe Ligges


> I will be happy to packup a runnable demonstration for any of you, but
> I wondered if it was just my lack of knowledge about "type" in
> predict.rpart; wondered if there was a simple and logical explanation.
>