R regex remove all punctuation except apostrophe [duplicate]

Question

I'm trying to remove all punctuation from a string except apostrophes. Here's my exastr2 <-

str2 <- "this doesn't not have an apostrophe,.!@#$%^&*()"
gsub("[[:punct:,^\\']]"," ", str2 )
# [1] "this doesn't not have an apostrophe,.!@#$%^&*()"

What am I doing wrong?

Answer 1

A "negative lookahead assertion" can be used to remove from consideration any apostrophes, before they are even tested for being punctuation characters.

gsub("(?!')[[:punct:]]", "", str2, perl=TRUE)
# [1] "this doesn't not have an apostrophe"

Answer 2

I am not sure if you can specify all punctuations except ' within a regexp the way you've done. I would check for alphanumerics + ' + space with negation:

gsub("[^'[:lower:] ]", "", str2) # per Joshua's comment
# [1] "this doesn't not have an apostrophe"