On 6 September 2013 at 14:20, Mark Clements wrote: | By my understanding, Rcpp is better suited to working with data-frames as | columns rather than working with data-frames as a set of rows. However, | occasionally it may be useful to work with the set of rows. How have others | considered this use case?
This has been discussed a few times here. The upshot is that Rcpp offers "proxy classes" as very thin and efficient shims over the internal R representation. Which is a __list of vectors__ for a data frame. So columns it is, because that is what we get from R / what R expects from us. Romain has opened a mad-scientist lab over at https://github.com/romainfrancois/RcppExtras where he is playing with a few things. Which may or may not end up here, which may or may not work now or in the future, and which may set your hair on fire. It's a lab to try things. | [As a motivating example based on simulations in C++, we want to pass | data-frames from R for use as look-up tables in C++ (cf. passing transformed | data back to R). The STL container std::map is well suited to this task, | particularly as it provides ordered keys. [ ... snip ... ] All good, and I am very much in favour of creating useful abstractions on top of the interface. But for better or worse, "eventually" everything has be a SEXP to go back to R so we may need a tranpose somewhere. Dirk -- Dirk Eddelbuettel | [email protected] | http://dirk.eddelbuettel.com _______________________________________________ Rcpp-devel mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
