[R] what missed ----- CART

[Uwe Ligges]

o ha wang wrote:
> Hi all,
>    
>   Can anyone who is familar with CART tell me what I missed in my tree code? 
>    
>   library (MASS)    
>   myfit <- tree (y ~ x1 + x2 + x3 + x4 )  

There is not function tree() in MASS. I guess you have loaded package 
"tree"?
Note that the author and maintainer of the tree package suggests to use 
package rpart instead.



>   # tree.screens ()   # useless
>   plot(myfit);  text (myfit, all= TRUE, cex=0.5, pretty=0)
>   # tile.tree (myfit, fgl$type)   # useless
>   # close.screen (all= TRUE)  # useless
> 
>    
>   My current tree plot resulted from above code shows as: 
>   1. overlapped #s caused by unsuitable length of branch.
>   2. no misclassification rates:  'misclass.tree' only brings up the error of ' misclassification error rate is appropriate for factor responses only', but my response y is 0/1 data.

If you data is 0/1, you should make it a factor otherwise the cose will 
assume you want a regression rather than a classification tree.


>   3. Unsuitable location of notations: there are not two notation of splitting criteria on the two branches when a node is split, instead only one notation of splitting criteria  is on the node location. 

It indicates which items go into the left branch.

Uwe Ligges


>    
>   thanks,
>   xiao yue
> 
>        
> ---------------------------------
> 
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