Re: st: RE: Stata code to run R code from within Stata and returncertain pieces of the results as Stata macros

[Daniel Becker <daniel.becker@uni-rostock.de>]

Hallo -

Thanks for this thread. I hope someone is trying to write that smart  
peace of software! But isn't rsource (findit rsource) already pretty  
smart?

Am 31.05.2008 um 02:20 schrieb Salah Mahmud:

> I think a smart solution is possible
> 1. Export a subset/all the data into a csv file and construct the
> necessary R code to import that data into R.
My understanding of the help of rsource is that the transfer of a  
dataset from stata to R is already possible. So no hard work here.


> 2. The Stata user specifies the R library that need to be loaded-- eg
> library(cmprsk) -- and the exact R code needed to perform the specific
> calculations. These could be stored in an *.R file or for simple tasks
> could be passed directly to Rbridge. So Rbridge could have 2 mutually
> exclusive options:
> i) Rcommand ("out<-crr(ftime,fstatus,cov,failcode=2) ")
> ii) Rcmdfilename( "mycode.R")
IN the rsource package, the R code is stored in a file that needs to  
be specified:

rsource using R_source_filename [ , noloutput lsource  
rpath(R_pathname) roptions(R_options) ]

This seems perfectly ok to me.

> 3. The user also specifies the result object returned by R (eg the out
> object in the out<-crr(ftime,fstatus,cov,failcode=2) that she would
> like Rbridge to return as global macros or r() macros. R is
> object-oriented so instead unlike Stata commands which return
> individual pieces of information, R functions typically return an
> object that contain all these pieces of information. So the object
> "out" in the call "out<-crr(ftime,fstatus,cov,failcode=2) " above
> stores all the info returned from calling the function crr. Things
> like out$coef , out$loglik etc which some call class members.
> Version 1 of Rbridge could return a specific class member (eg
> out$loglik). A more advanced implementation will parse (within R) the
> target object and extract all the members' names and values (contents)
> into a text file which would include info on each member's name, data
> type and value. The necessary commands are added to source.R. This may
> include calls to custom R functions that facilitate the parsing and
> extraction of the members of the result object. But as I said this is
> not essential for version 1.
it seems like this is the tricky part. rsource can already list the  
output of the R-code executed in the stata results window, but that's  
it. It is not yet possible to have the results produced by R in a r()  
macro.


> 4. Stata runs R and pass along source.R for execution which results in
> the above results text file.
Hm - isn't this already possible? If the R-code contains the necessary  
commands, the result of the execution of r could be that text file.  
Hence the ral work is to get the proper R-code that contains all  
results such that they can be imported back into stata.


> 4. Stata reads the text file and generates macros with the same name,
> data type and values which Rbridge could also leave behind as r()
> macros.
Once the textfile contains the information, this must be possible? Is  
there an example of reading a text file and putting something written  
there in a stata-macro?


> I'm sure the devil is in the details (eg there are issues with
> coordinating the running of Stata and R). For instance, Stata may have
> to go to sleep until R signals that the code execution is over etc.
> But the above does not seem any more daunting than the average ado out
> there.
Wouldn't the easy check be: Stata, please white until the file /file/ 
that/is/the/result/of/executing/R/ exists?
A variant of the pause command? How about an option waitfor(/file/that/ 
is/the/result/of/executing/R/results.txt) for rsource?

It is my impression that most things you want are already present in  
rsource and that the real hard work is to write the necessary R-code  
and then get the information back into stata. And for this, it very  
much depends on what exactly you want to do in R.

Best,

Daniel
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