Hi again, On 14 April 2011 at 23:20, Patrick Ye wrote: | Hi Dirk, | | Thanks so much for the reply, I really appreciate it. | | I thought that I was misusing Rcpp, as all the examples I found seemed | to be for writing C++ functions to be used in R -- not accessing R | functions in C++. | | Thanks so much for your suggestions on RInside, I just found out about | it a few minutes ago myself, and my code is no longer segfaulting. :)
Excellent :) | One more question if you don't mind. Where can I find documentation on | accessing the member variables of an R instance using Rcpp? Let me give | you a concrete example of what I need to do. Slowly work through the 10+ examples in examples/standard/ -- there are examples for all cases. The first approach is to use the parseEval() approach which returns the last statement, as an R function would. Rcpp then helps with the implicit or explicit cast to whichever C++ type is suitable. The second approach is ... simple lookup by name using []. | I'm trying to use the stl function in R to calculate the seasonal, | trend, remainder and weight parameters of a time series object. I've You are spot on. Perfect use case: deploy something that R is strong at, and pull it into C++. Wanna contribute yet another example? You will get eternal fame by the Copyright line in that source file ;-) | gotten as far as creating the time series object from a list of numbers, | and then passing the time series to the stl function using a | Rcpp::Language object, and then grabbing the results using the eval() | function of the Rcpp::Language object. If it was in R, I could access | the weights using notations like "foo$weights", and the time series | object as "foo$time.series". If it was in rpy2, I could use the | dictionary notations to access the "weights" and "time.series" members | of stl's return value. However, I cannot seem to find any | function/notation in Rcpp that allows me to do the same thing. | | I guess I could generate a string that represents all the things I need | to do in R, and use the parseEval function of the RInside object to get | the final results. However, that just doesn't seem to be very elegant. | Is there another way? >From the top of my head, what I would do is to pass a string containing several R commands to the embedded R instance. It should compute all values of interest. And the ones I'd want in C++ I'd then transfer one by one using one of the approaches above. Actually, you could even construct a big encompassing list object in R, and pass that. Rcpp then helps you decompose it on the C++ side into individual pieces. More than one way to skin the cat... Cheers, Dirk -- Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com _______________________________________________ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
