On Thu, Feb 6, 2014 at 8:53 AM, Arunkumar Srinivasan <[email protected]> wrote: > Not really. Because it still doing a "by". Meaning, for every grouping in > "by" - abs(x-y) will be evaluated. If there are 1e5 groups, there'll be 1e5 > calls. And that can be expensive depending on the function + the time to > call eval from within C. > > However, since it's not necessary to do a by-without-by, we can perform the > join and then compute once the difference between columns. There's no > grouping, no eval from C, and no multiple calls to abs. Hope this clears it > up? > >
In that case what is the proposed user interface? I thought that the idea was that one would have to explicitly specify the by= clause for by-within-by it to occur. In the code I had just posted there is a join = "nearest" but no by= clause is specified. _______________________________________________ datatable-help mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
