Many thanks. Unfortunately, I cannot work directly on these expressions since they’re only created from other strings. Would I first have to transform these strings to unevaluated expressions? Von: William Dunlap [mailto:wdun...@tibco.com] Gesendet: Freitag, 27. Februar 2015 23:39 An: Alrik Thiem Cc: r-help@r-project.org Betreff: Re: [R] Substring replacement in string If your string will always represent an R expression, you could work with the expression directly with functions like all.names() and substitute(). f <- function (expr) { toReplace <- setdiff(all.names(expr), c("pmin", "pmax")) toReplace <- grep(value = TRUE, "[a-z]", toReplace) names(toReplace) <- toReplace replacementList <- lapply(toReplace, function(name) call("-", 1, as.name(toupper(name)))) do.call(substitute, list(expr, replacementList)) } > In <- quote(pmin(pmax(pmin(x1, X2), pmin(X3, X4)) == Y, pmax(Z1, z1))) > Desired <- quote(pmin(pmax(pmin(1 - X1, X2), pmin(X3, X4)) == Y, pmax(Z1, 1 - > Z1))) > all.equal(Desired, f(In)) [1] TRUE
Bill Dunlap TIBCO Software wdunlap tibco.com On Fri, Feb 27, 2015 at 2:19 PM, Alrik Thiem <alrik.th...@gmail.com> wrote: Dear R-help list, I would like to replace all lower-case letters in a string that are not part of certain fixed expressions. For example, I have the string: "pmin(pmax(pmin(x1, X2), pmin(X3, X4)) == Y, pmax(Z1, z1))" Where I would like to replace all lower-case letters that do not belong to the functions "pmin" and "pmax" by 1 - toupper(...) to get "pmin(pmax(pmin(1 - X1, X2), pmin(X3, X4)) == Y, pmax(Z1, 1 - Z1))" Any ideas on how I could achieve that? Many thanks and best wishes, Alrik ******************************** Alrik Thiem Post-Doctoral Researcher Department of Philosophy University of Geneva Rue de Candolle 2 CH-1211 Geneva +41 76 527 80 83 http://www.alrik-thiem.net http://www.compasss.org ______________________________________________ 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.