R help - Feb 2008 - what missed ----- CART

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 )  
  # 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.
  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.
   
  thanks,
  xiao yue

       
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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
> 
>        
> ---------------------------------
> 
> 	[[alternative HTML version deleted]]
> 
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