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Request to review a patch for rpart

3 messages · Gabriel Becker, Kirill Müller

Original
Kirill Müller
# 
Dear list


For my work, it would be helpful if rpart worked seamlessly with an 
empty model:

library(rpart); rpart(formula=y~0, data=data.frame(y=factor(1:10)))

Currently, an unrelated error (originating from na.rpart) is thrown.

At some point in the near future, I'd like to release a package to CRAN 
which uses rpart and relies on that functionality. I have prepared a 
patch (minor modifications at three places, and a test) which I'd like 
to propose for inclusion in the next CRAN release of rpart. The patch 
can be reviewed at https://github.com/krlmlr/rpart/tree/empty-model, the 
files (based on the current CRAN release 4.1-8) can be downloaded from 
https://github.com/krlmlr/rpart/archive/empty-model.zip.

Thanks for your attention.


With kindest regards

Kirill M?ller
2 days later
Gabriel Becker
# 
Kirill,

Perhaps I'm just being obtuse, but what are you proposing rpart do in the
case of an empty model?  Return a "tree" that always guesses the most
common label, or doesn't guess at all (NA)? It doesn't seem like you'd need
rpart for either of those.

~G


On Wed, Aug 13, 2014 at 3:51 AM, Kirill M?ller <
kirill.mueller at ivt.baug.ethz.ch> wrote:

            

      
      
      
    

        

      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Kirill Müller
    

    

      
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Gabriel


Thanks for your feedback. Indeed, I was not particularly clear here. The 
empty model is just a very special case in a more general setting. I'd 
have to work around this deficiency in my code -- sure I can do that, 
but I thought a generic solution should be possible. In particular, I'm 
using predict.rpart(..., type = "prob") -- this just reflects the 
observed relative frequencies.


Cheers

Kirill

        
On 08/15/2014 06:44 PM, Gabriel Becker wrote: