search for: strextract

...eptually corresponds with missing data) and facility of use in data.frames. The behavior of regmatches(..., gregexpr(...)) is not objectionable to me, as lists do not drop indices when they contain character(0) vectors. Alternatively, perhaps this should be reflected in the (currently non-exported) strextract. Best, CG

...instead insert an NA_character_ value (similar to stringr::str_extract). This alternative regmatches could be implemented through an optional drop argument, a new function, or mentioned in the documentation (a la resample in ?sample).? Alternatively, at the moment, there is a non-exported function strextract in utils which is very similar to stringr::str_extract. It would be great if this function, once exported, were to include a drop argument to prevent dropping positions with no matches.? An example solution (last option): strextract <- function(pattern, x, perl = FALSE, useBytes = FALSE, drop...

I'd be happy to entertain patches or at least more specific suggestions to improve strextract() and strcapture(). I hadn't exported strextract(), because I wasn't quite sure how it should behave. This feedback should be helpful. Thanks, Michael On Thu, Aug 29, 2019 at 2:20 PM Cyclic Group Z_1 via R-devel <r-devel at r-project.org> wrote: > > Thank you, I am aware that...

...d 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

...aracter_ value (similar to > stringr::str_extract). This alternative regmatches could be implemented > through an optional drop argument, a new function, or mentioned in the > documentation (a la resample in ?sample). > > Alternatively, at the moment, there is a non-exported function strextract > in utils which is very similar to stringr::str_extract. It would be great > if this function, once exported, were to include a drop argument to prevent > dropping positions with no matches. > > An example solution (last option): > > strextract <- function(pattern, x, perl...

I don't care much for regmatches and haven't tried strextract, but I think replacing the character(0) by NA_character_ is almost always inappropriate if the match information comes from gregexpr. I think strcapture() does a pretty good job of what I think you are trying to do. Perhaps adding an argument to map no match to NA instead of "" would gi...

...aracter_ value (similar to > stringr::str_extract). This alternative regmatches could be implemented > through an optional drop argument, a new function, or mentioned in the > documentation (a la resample in ?sample). > > Alternatively, at the moment, there is a non-exported function strextract > in utils which is very similar to stringr::str_extract. It would be great > if this function, once exported, were to include a drop argument to prevent > dropping positions with no matches. > > An example solution (last option): > > strextract <- function(pattern, x, perl...

...ALSE)) Name Address 1 Groucho groucho at marx.com 2 chico at marx.com 3 Harpo Bill Dunlap TIBCO Software wdunlap tibco.com On Thu, Aug 15, 2019 at 1:04 PM William Dunlap <wdunlap at tibco.com> wrote: > I don't care much for regmatches and haven't tried strextract, but I think > replacing the character(0) by NA_character_ is almost always inappropriate > if the match information comes from gregexpr. > > I think strcapture() does a pretty good job of what I think you are trying > to do. Perhaps adding an argument to map no match to NA instead...

...nd it returns a "matching region" which would be empty when there is no match. We could allow strcapture() to accept an atomic vector as a prototype, which would do what you want for regexec() (NA on no match, empty string on empty capture). Then we could call the regexpr()-based function strextract(). What do you think? Michael On Thu, Aug 29, 2019 at 3:27 PM Cyclic Group Z_1 <cyclicgroup-z1 at yahoo.com> wrote: > > Thank you! I greatly appreciate your consideration, though of course it is up to you. I think many people switch to stringr/stringi simply because functions in thos...

Thank you! I greatly appreciate your consideration, though of course it is up to you. I think many people switch to stringr/stringi simply because functions in those packages have some consistent design choices, for example, they do not drop empty/missing matches, which facilitates array-based programming. For example, in the cases where one needs to make a new column in a data.frame (data.table,

I think that's a good reason for not including this in regmatches; you're right, its name is somewhat suggestive of yielding matches. Also, that sounds like a great design for strcapture with an atomic prototype. Best, CG

After some discussion within R core, we decided that a "nomatch" argument on regmatches() may be a good initial step. We might add a new function later that combines the regexpr() and regmatches() steps. The gregexpr() and regexec() inputs are both lists so it's not clear whether a "nomatch" value would be relevant (the elements are empty) in those cases. On Mon, Sep 2,