Ken, On 19 February 2013 at 22:35, Ken Williams wrote: | I have a need to loop through all the entries of a DataFrame by row, then | column. I know two different ways:
There have been prior discussions of this topic, as well as example posts -- even leading to a Rcpp Gallery article. Did you read any of these? It wasn't clear from your post. | I?m also curious why it?s a syntax error in Case A to just write `df[j][i]` or Eeeek. I prefer the more C++-y way of writing df(j,i). Square brackets only work for vectors, and even then you may be better off with x(i) for consistency. Overall, your premise may be wrong too. "We all know" that a data.frame is not the fastest data structure in R, so by forcing ourselves to the same access are we not handycapping ourselves. Once you are in C++, you can use whatever C++ datatype you like. A data.frame really is just a list of vectors, each of the vectors has eg a begin(0 iterator which you can (fairly costlessly) instantiate STL types. And those give you performance guarantees. Hope this helps, 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
