[R] Question re labels in r-part (continuation of a thread from a while back)

[Thomas W Blackwell]

Peter  -

(Just gessing about the structure of rpart objects ...)  How about

tr.totpart.pruned$frame <- cbind(tr.totpart.pruned$frame,
	 	 	 meanpart = exp(tr.totpart.pruned$frame$yval)-1)

This appends meanpart as an additional column of tr.totpart.pruned$frame.
After this step, I would expect the plot command below to work.
I haven't tried this out myself, though.

-  tom blackwell  -  u michigan medical school  -  ann arbor  -

On Fri, 19 Dec 2003, Peter Flom wrote:

> Hello again
>
> I have modeled a tree using rpart, with the DV being a log
> transformation of the variable I am really interested in (I transformed
> the DV due to extreme skewness).  By default, text.rpart labels the
> nodes with the value of yval, which in this case is not what I want; I'd
> like the labels to be on the original metric, but label in text.rpart
> requires a  "column name of x$frame", and the original DV is not on that
> frame.
>
> So, I tried the following:
>
> {create the tree}
> tr.totpart <- rpart(log(totpart +1)  ~ sexfact + age + windle +
> eabused
>     + as.factor(pabau) + positive + controlling + lenient +
> druguse.ever
>     + anycsw,
>     xval = 10,  cp = 0.000000001, data = duhray)
>
>
>
> {prune the tree}
> tr.totpart.pruned <- prune (tr.totpart, cp = .02)
>
>
> {ad the original metric to the frame}
>
>
> meanpart <- exp(tr.totpart.pruned$frame$yval)-1
> tr.totpart.pruned$frame <- cbind(tr.totpart.pruned$frame, meanpart)
>
>
> and thought this was good because summary(tr.totpart.pruned$frame)
> lists meanpart as one of the columns.
>
> BUT when I tried
>
>
> plot(tr.totpart.pruned, compress = T, uniform = T, nspace = .5, margin
> = .1)
> text(tr.totpart.pruned, splits = T, all = T, pretty = 0, digits = 4,
> use.n = T,  fancy = T, label = meanpart)
>
> I got an error
>
> Error in text.rpart(tr.totpart.pruned, splits = T, all = T, pretty = 0,
>  :
>         Label must be a column label of the frame component of the
> tree
>
>
>
>
>
> Any thoughts or insights or help appreciated, as always
>
> Peter
>
> PS Given the recent posts on the thread about how to ask questions, I
> should perhaps add that I have looked thru ?rpart, and through Atkinson
> & Therneau (1997): An Introduction to recursive partitioning using the
> RPART routines
>
>
>
> Peter L. Flom, PhD
> Assistant Director, Statistics and Data Analysis Core
> Center for Drug Use and HIV Research
> National Development and Research Institutes
> 71 W. 23rd St
> www.peterflom.com
> New York, NY 10010
> (212) 845-4485 (voice)
> (917) 438-0894 (fax)
>
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