I do think keeping the default behavior is desirable for backwards compatibility; my suggestion is not to change default behavior but to add an optional argument that allows a different behavior. Although this can be implemented in a user-defined function, retaining empty matches facilitates programmatic use, and seems to be something that should be available in base R. It is available, for example, in MATLAB, a comparable array language.
Alternatively, perhaps a nomatch (or maybe emptymatch) argument in the spirit of `[.data.table`? That is, an argument nomatch where nomatch = NULL (the default) results in drops for vector outputs and character(0) for list outputs and nomatch = NA results in insertion of NA_character_, and nomatch = '' results in insertion of empty string. I can submit proposed patch code if others think this is a good idea. What are your thoughts on the proposed alteration to (currently nonexported) strextract? I assume (maybe wrongly) that the plan is to eventually export that function. Thank you, CG ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
