R: Change multiple strings to one other string

Question

Relative R newbie here. How do I change multiple strings to one string in a character vector?

For example:

college <- c("CAS", "HHS", "CB", "CAS,HHS", "CB", "CAS,CB", "CAS,HHS,CB", "HHS")

I want to keep "CAS", "HHS", and "CB", and change everything else to "MULT". I've tried:

dontchange <- c("CAS", "HHS", "CB")
college[college!=dontchange] <- c("MULT")
college
[1] "CAS"  "HHS"  "CB"   "MULT" "MULT" "MULT" "MULT" "HHS" 

The fifth element (second "MULT") should be CB.

Any help would be appreciated. Thanks!

Answer 1

I think @akrun has explained in every bit regarding != and %in%.

Here are some option that may help

replace(college, !college %in% dontchange, "MULT")

or

replace(college, is.na(match(college, dontchange)), "MULT")