Yes, I agree. Maybe the clumsiness of my example might help clarify the importance of clarifying the context/understanding the difficulty.
Cheers, Bert On Tue, Oct 29, 2019 at 5:22 PM Duncan Murdoch <murdoch.dun...@gmail.com> wrote: > On 29/10/2019 12:46 p.m., Bert Gunter wrote: > > Does something like the following make any sense for your context? > > > >> z <- "(xy+ s)/ (ab +log(4.13))" > >> > >> lapply(parse(text = z), FUN = function(x)strsplit(deparse(x), split = > > "[[:space:]]+")) > > [[1]] > > [[1]][[1]] > > [1] "(xy" "+" "s)/(ab" "+" "log(4.13))" > > That's the wrong way to do it. Notice the 3rd element, "s)/(ab", which > combines two partial operands and an operator. Deparsing doesn't always > introduce spaces, as your reprex assumes. > > I think Witold's request is quite hard to do. The right way to handle > expressions is as hierachical objects, like those returned from > parse(text = z). Turning those into character vectors of lexical tokens > doesn't make sense. > > Perhaps if Witold explained the context of what he is trying to do > someone could give a suggestion about a better approach. > > Duncan Murdoch > > > > > > > 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 Tue, Oct 29, 2019 at 9:23 AM Ivan Krylov <krylov.r...@gmail.com> > wrote: > > > >> On Tue, 29 Oct 2019 13:55:27 +0100 > >> Witold E Wolski <wewol...@gmail.com> wrote: > >> > >>> Since R knows how to parse expressions these type of expressions I > >>> would like to reuse some existing functions and not to use gsub or > >>> strsplit etc. > >> > >> You might be interested in the `parse` function: > >> > >> x <- "(a+b) * c/(d * (e - f))" > >> str(parse(text = x)) > >> # length 1 expression((a + b) * c/(d * (e - f))) > >> # - attr(*, "srcref")=List of 1 > >> # ..$ : 'srcref' int [1:8] 1 1 1 23 1 23 1 1 > >> # .. ..- attr(*, "srcfile")=Classes 'srcfilecopy', 'srcfile' > >> <environment: 0x55ebecdac210> > >> # - attr(*, "srcfile")=Classes 'srcfilecopy', 'srcfile' > >> <environment:0x55ebecdac210> > >> # - attr(*, "wholeSrcref")= 'srcref' int [1:8] 1 0 2 0 0 0 1 2 > >> # ..- attr(*, "srcfile")=Classes 'srcfilecopy', > >> 'srcfile'<environment:0x55ebecdac210> > >> parse(text = x)[[1]] > >> # (a + b) * c/(d * (e - f)) > >> parse(text = x)[[1]][1] > >> # `/`() > >> parse(text = x)[[1]][2] > >> # ((a + b) * c)() > >> parse(text = x)[[1]][3] > >> # (d * (e - f))() > >> > >> Quoting ?expression, > >> > >>>> As an object of mode ‘"expression"’ is a list, it can be subsetted > >>>> by ‘[’, ‘[[’ or ‘$’, the latter two extracting individual calls etc. > >> > >> -- > >> Best regards, > >> Ivan > >> > >> ______________________________________________ > >> 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. > >> > > > > [[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. > > > > [[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.
