[R] Substring replacement in string

[Alrik Thiem]

Dear Gabor,

Many thanks. Works like a charm, but I can't get it to work with

"pmin(pmax(pmin(a,B),pmin(a,C,d))==Y,pmax(E,e))"

i.e., with strings where there're no integers following the components in the pmin/pmax functions. Could this be generalized to handle both cases?

Best wishes,
Alrik

-----Ursprüngliche Nachricht-----
Von: Gabor Grothendieck [mailto:ggrothendieck at gmail.com] 
Gesendet: Samstag, 28. Februar 2015 13:35
An: Alrik Thiem
Cc: r-help at r-project.org
Betreff: Re: [R] Substring replacement in string

On Fri, Feb 27, 2015 at 5:19 PM, Alrik Thiem <alrik.thiem at gmail.com> wrote:
> 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))"
>

Assuming x is the input string:

gsub("(\\b[a-oq-z][a-z0-9]+)", "1-\\U\\1", x, perl = TRUE)
## [1] "pmin(pmax(pmin(1-X1, X2), pmin(X3, X4)) == Y, pmax(Z1, 1-Z1))"



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