I agree that this is not a complete implementation; it isn't meant to be, although it might still be a worth incorporating this into Rcpp with the appropriate fixes in place.
For instance, the vector recycling issue is far from the greatest limitation of this code: it handles character vectors wrong, The R routine converts character vectors into factors unless overridden; I wrote the precursor of this particular routine because I wanted to handle strings faithfully, and so writing a stupid R routine to coerce lists of lists of constant length to data frames. On Thu, Jan 31, 2013 at 3:21 AM, Romain Francois <rom...@r-enthusiasts.com>wrote: > Le 15/01/13 16:20, John Merrill a écrit : > > It appears that DataFrame::create is a thin layer on top of the R >> data.frame call. The guarantee correctness, but also means the >> performance of an Rcpp routine which returns a large data frame is >> limited by the performance of data.frame -- which is utterly horrible. >> >> In the current version of R, there's a trivial, but borderline evil, >> work around: build a list of lists meeting the basic requirements of a >> data frame (they all need to be of the same length, and each component >> list needs to be named) and set the type of the object to "data.frame". >> >> I have two questions: >> (1) Is it reasonable to anticipate that this hack will continue to work >> for the near future in R? >> (2) If so, would a patch to that effect be of interest to the developers? >> > > The reason we used a callback to data.frame is close to lazyness on our > part. With the R function, for example we know that columns of different > sizes will be handled properly, with recylcling, etc ... > > Just making a named list of vectors is not enough. We have to make sure > they all have the same length. > > Perhaps it would be worth checking this and make better DataFrame::create > functions. > > > > Also, you can use a shortcut to assign row names, i.e. mimic this in C++ > (the second line contains the magic): > > > d <- list( x = 1:10, y = 1:10 ) > > attr( d, "row.names" ) <- c( NA, -10L ) > > attr( d, "class" ) <- "data.frame" > > d > x y > 1 1 1 > 2 2 2 > 3 3 3 > 4 4 4 > 5 5 5 > 6 6 6 > 7 7 7 > 8 8 8 > 9 9 9 > 10 10 10 > > > Romain > > -- > Romain Francois > Professional R Enthusiast > +33(0) 6 28 91 30 30 > > R Graph Gallery: > http://gallery.r-enthusiasts.**com<http://gallery.r-enthusiasts.com> > > blog: > http://romainfrancois.blog.**free.fr<http://romainfrancois.blog.free.fr> > |- http://bit.ly/RE6sYH : OOP with Rcpp modules > `- http://bit.ly/Thw7IK : Rcpp modules more flexible > >
_______________________________________________ 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
