Feature request: `str_replace_n()` to replace the nth match

[DanChaltiel]

Hi, and thank you for your work on stringr!

I’d like to suggest a new function: str_replace_n(), which would allow replacing the nth match of a pattern.

This would cover common but currently awkward use cases, such as replacing only the last match or the second match.

Expected output:

str_replace_n("a-b-c-d", "-", "+", n = 1) #with n=1, we get the same as str_replace()
#> "a+b-c-d"

str_replace_n("a-b-c-d", "-", "+", n = 2)
#> "a-b+c-d"

str_replace_n("a-b-c-d", "-", "+", n = -1)
#> "a-b-c+d"

Would this kind of feature be aligned with the design goals of the package?

If not, would you consider at least re-exporting stringi::stri_replace_last()?

Thanks again for considering it!

[hadley]

Unfortunately this feels a bit too special purpose to me.

[DanChaltiel]

@hadley I’d really appreciate it if you could consider reopening this issue, especially regarding re-exporting stringi::stri_replace_last().
Maybe you could ask around for a second opinion?

I get it that the nth match might be special, but replacing the last occurrence is very common in my practice (and requires hacky solutions).