[R] Seeking Code for Chaid or Similar

[Achim Zeileis]

On Wed, 27 Aug 2008, David Cobey wrote:

> Quick disclaimer: I'm new to the list and I'm not sure if I'm sending this
> to the correct forum.  If there is a better place for this questions, please
> let me know!
>
> Dear R List,
>    I'm interested in modifying a regression tree algorithm to use the
> difference between a control and a dosed sample as its dependent variable.
> I was wondering if anyone knew where I could find code to implement a basic
> chaid algorithm.  Is it possible to access the code inside of R?  Is there
> another place I can find the basic algorithm already coded.
>    I'd prefer a chaid-like algorithm over a c&rt like algorithm, as my
> sample is small.  I'm  a reasonably good programmer, a background in C++ and
> experience in many different languages.
>    I'd very much appreciate any thoughts.

ctree() in package "party" implements in inference-based tree algorithm. 
It's based on conditional inference, but not unsimilar to CHAID in the 
case of categorical variables. See its references and vignette for more 
details.

Torsten and I are also working on some basic tree infrastructure which 
could/should eventually also be used for implementing classical CHAID but 
that will take some more time.

hth,
Z

> Thank you!
> David Cobey
>
> PS. Of course, if this has been done before, I'd be very grateful for the
> opportunity to save myself the trouble of reprogramming it myself!
>
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