I am not the one who proved this... I can only respond to your suggested counterexamples. -- Sent from my phone. Please excuse my brevity.
On September 5, 2016 9:01:12 AM PDT, Bert Gunter <bgunter.4...@gmail.com> wrote: >Jeff: > >It is not obvious to me that the ability to *match* an arbitrary >pattern (including one of several different ones via "|" , per the >link you included) implies that sub() and friends can extract it, e.g. >via the /N construct or otherwise. I would appreciate it if you or >someone else could show me how this can be done. > >Cheers, >Bert > > >Bert Gunter > >"The trouble with having an open mind is that people keep coming along >and sticking things into it." >-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > > >On Mon, Sep 5, 2016 at 8:37 AM, Jeff Newmiller ><jdnew...@dcn.davis.ca.us> wrote: >> Yes, sorry I did not look closer... regex can match any finite >language, so there are no data sets you can feed to R that cannot be >matched. [1] You may find it hard to see the pattern, or you may want >to build the pattern programmatically to alleviate tedium for yourself, >but regexes are not the constraint. >> >> http://www.cs.nuim.ie/~jpower/Courses/Previous/parsing/node18.html >> -- >> Sent from my phone. Please excuse my brevity. >> >> On September 4, 2016 10:41:45 PM PDT, Bert Gunter ><bgunter.4...@gmail.com> wrote: >>>Well, he did provide an example, and... >>> >>> >>>> z <- c('TX.WT.CUT.mean','mg.tx.cv') >>> >>>> sub("^.+?\\.(.+)\\.[^.]+$","\\1",z) >>>[1] "WT.CUT" "tx" >>> >>> >>>## seems to do what was requested. >>> >>>Jeff would have to amplify on his initial statement however: do you >>>mean that separate patterns can always be combined via "|" ? Or >>>something deeper? >>> >>>Cheers, >>>Bert >>>Bert Gunter >>> >>>"The trouble with having an open mind is that people keep coming >along >>>and sticking things into it." >>>-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) >>> >>> >>>On Sun, Sep 4, 2016 at 9:30 PM, Jeff Newmiller >>><jdnew...@dcn.davis.ca.us> wrote: >>>> Your opening assertion is false. >>>> >>>> Provide a reproducible example and someone will demonstrate. >>>> -- >>>> Sent from my phone. Please excuse my brevity. >>>> >>>> On September 4, 2016 9:06:59 PM PDT, Jun Shen ><jun.shen...@gmail.com> >>>wrote: >>>>>Dear list, >>>>> >>>>>I have a vector of strings that cannot be described by one pattern. >>>So >>>>>let's say I construct a vector of patterns in the same length as >the >>>>>vector >>>>>of strings, can I do the element wise pattern recognition and >string >>>>>substitution. >>>>> >>>>>For example, >>>>> >>>>>pattern1 <- "([^.]*)\\.([^.]*\\.[^.]*)\\.(.*)" >>>>>pattern2 <- "([^.]*)\\.([^.]*)\\.(.*)" >>>>> >>>>>patterns <- c(pattern1,pattern2) >>>>>strings <- c('TX.WT.CUT.mean','mg.tx.cv') >>>>> >>>>>Say I want to extract "WT.CUT" from the first string and "tx" from >>>the >>>>>second string. If I do >>>>> >>>>>sub(patterns, '\\2', strings), only the first pattern will be used. >>>>> >>>>>looping the patterns doesn't work the way I want. Appreciate any >>>>>comments. >>>>>Thanks. >>>>> >>>>>Jun >>>>> >>>>> [[alternative HTML version deleted]] >>>>> >>>>>______________________________________________ >>>>>R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >>>>>https://stat.ethz.ch/mailman/listinfo/r-help >>>>>PLEASE do read the posting guide >>>>>http://www.R-project.org/posting-guide.html >>>>>and provide commented, minimal, self-contained, reproducible code. >>>> >>>> ______________________________________________ >>>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >>>> https://stat.ethz.ch/mailman/listinfo/r-help >>>> PLEASE do read the posting guide >>>http://www.R-project.org/posting-guide.html >>>> and provide commented, minimal, self-contained, reproducible code. >> ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
