[R] Problems with tree package

[Torsten Hothorn]

> 	Hi,
> 	I'm getting a problem with the tree package under windows nt
> 	I'm using the package to produce a tree. The training set has +- 4000 
> examples.
> 	I use the instruction
> 
> 	hm.tr <-tree(X1~.,teste2)
> 
> 	wich produces me this tree
> 
>    1) root 4272 4037.000 0 ( 0.819288 0.180712 )
>      2) X2: 0 1640 2261.000 0 ( 0.543902 0.456098 )
>        4) X4: 0 357  170.600 1 ( 0.064426 0.935574 ) *
>        5) X4: 1 1283 1614.000 0 ( 0.677319 0.322681 )
>         10) X8: 0 849 1172.000 0 ( 0.538280 0.461720 )
>           20) X34: 0 701  965.800 1 ( 0.453638 0.546362 )
>             40) X20: 0 618  823.800 1 ( 0.385113 0.614887 )
>               80) X31: 0 516  629.100 1 ( 0.298450 0.701550 )
>                160) X3: 0 247  166.200 1 ( 0.105263 0.894737 ) *
>                161) X3: 1 269  372.300 1 ( 0.475836 0.524164 )
>                  322) X35: 0 200  262.500 0 ( 0.635000 0.365000 )
>                    644) X30: 0 99  131.900 1 ( 0.383838 0.616162 ) *
>                    645) X30: 1 101   73.640 0 ( 0.881188 0.118812 ) *
>                  323) X35: 1 69   10.450 1 ( 0.014493 0.985507 ) *
>               81) X31: 1 102   95.060 0 ( 0.823529 0.176471 ) *
>             41) X20: 1 83   25.810 0 ( 0.963855 0.036145 ) *
>           21) X34: 1 148   67.840 0 ( 0.939189 0.060811 ) *
>         11) X8: 1 434  174.100 0 ( 0.949309 0.050691 ) *
>      3) X2: 1 2632  273.300 0 ( 0.990881 0.009119 )
>        6) X9: 0 2553  152.600 0 ( 0.995300 0.004700 ) *
>        7) X9: 1 79   67.310 0 ( 0.848101 0.151899 )
>         14) X32: 0 12    6.884 1 ( 0.083333 0.916667 ) *
>         15) X32: 1 67   10.390 0 ( 0.985075 0.014925 ) *
> 
> when i used this examples to classificate
> 
>  > classifica
>    X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21
> 1  0  1  0  0  0  0  0  0  0   0   0   0   0   0   0   0   0   0   0   0   0
>    X22 X23 X24 X25 X26 X27 X28 X29 X30 X31 X32 X33 X34 X35 X36
> 1   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0
>  > predict(hm.tr,classifica,"where")
> 1
> 3
>  > classifica[1,2]<-0
>  > predict(hm.tr,classifica,"where")
> 1
> 1

hm.tr$where corresponds to the row of hm.tr$frame where rownames codes for
the leaf numbers, e.g.

R> example(rpart)
R> fit
n= 81 

node), split, n, loss, yval, (yprob)
      * denotes terminal node

 1) root 81 17 absent (0.7901235 0.2098765)  
   2) Start>=8.5 62  6 absent (0.9032258 0.0967742)  
     4) Start>=14.5 29  0 absent (1.0000000 0.0000000) *
     5) Start< 14.5 33  6 absent (0.8181818 0.1818182)  
      10) Age< 55 12  0 absent (1.0000000 0.0000000) *
      11) Age>=55 21  6 absent (0.7142857 0.2857143)  
        22) Age>=111 14  2 absent (0.8571429 0.1428571) *
        23) Age< 111 7  3 present (0.4285714 0.5714286) *
   3) Start< 8.5 19  8 present (0.4210526 0.5789474) *

but

R> fit$frame[,1:3]
      var  n wt
1   Start 81 81
2   Start 62 62
4  <leaf> 29 29
5     Age 33 33
10 <leaf> 12 12
11    Age 21 21
22 <leaf> 14 14
23 <leaf>  7  7
3  <leaf> 19 19

has the node numbers as rownames and 

> fit$where
 1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
26 
 9  7  9  9  3  3  3  3  3  8  8  3  9  5  3  3  3  7  3  5  3  9  8  9  9
5 

...

refers to row-numbers !

Torsten


> 
> i have this result.
> In the first example, as X2 is 1 and X9 is 0 shouldn't result 20?
> Is this a problem of the package or i'm i using it inciorrectly?
> 
> Thanks
> Hugo 
> 
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