[R] Accessing terminal datasets in Ctree()

[Achim Zeileis]

On Mon, 2 May 2016, Preetam Pal wrote:

> Great, thank you so much Achim.But one issue, in case I do not know how many
> terminal nodes would be there, what do I do? Note that I do not need the
> datasets corresponding to the intermediate nodes only need the terminal
> datasets.

With predict(ct, type = "node") you can set up a new variable, e.g.,

iris$node <- factor(predict(ct, type = "node"))

and then use this to obtain the subset corresponding to each of the 
terminal nodes.

> Regards,
> Preetam 
> 
> On Tue, May 3, 2016 at 3:08 AM, Achim Zeileis <Achim.Zeileis at uibk.ac.at>
> wrote:
>       On Mon, 2 May 2016, Preetam Pal wrote:
>
>             Hi guys,
>
>             If I am applying ctree() on a data (specifying some
>             control parameters like
>             maxdepth), is there a way I can programmatically
>             access the (smaller)
>             datasets corresponding to the terminal nodes in the
>             tree? Say, if there are
>             7 terminal nodes, I need those 7 datasets (of
>             course, I can look at the
>             respective node-splitting attributes and write out a
>             filtering function -
>             but clearly too much to ask for if I have a large
>             number of terminal
>             nodes). Intention is to perform regression on each
>             of these terminal
>             datasets.
> 
>
>       If you use the "partykit" implementation you can do:
>
>       library("partykit")
>       ct <- ctree(Species ~ ., data = iris)
>       data_party(ct, id = 6)
>
>       to obtain the data associated with node 6 for example. You can
>       also use ct[6] to obtain the subtree and ct[6]$data for its
>       associated data.
>
>       For setting up a factor with the terminal node IDs, you can also
>       use predict(ct, type = "node") and then use that in lm() etc.
>
>       Finally, note that there is also lmtree() and glmtree() for
>       trees with (generalized) linear models in their nodes.
>
>             Regards,
>             Preetam
>
>             --
>             Preetam Pal
>             (+91)-9432212774
>             M-Stat 2nd Year,                                   
>                      Room No. N-114
>             Statistics Division,                               
>                        C.V.Raman
>             Hall
>             Indian Statistical Institute,                       
>                      B.H.O.S.
>             Kolkata.
>
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>
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> 
> 
> --
> Preetam Pal                                                  
> (+91)-9432212774
> M-Stat 2nd Year,                                             Room No. N-114
> Statistics Division,                                           C.V.Raman
> HallIndian Statistical Institute,                                 B.H.O.S.
> Kolkata.
> 
>