r - Remove everything after space in string

Question

I would like to remove everything after a space in a string.

For example:

"my string is sad"

should return

"my"

I've been trying to figure out how to do this using sub/gsub but have been unsuccessful so far.

Answer 1

You may use a regex like

sub(" .*", "", x)

See the regex demo.

Here, sub will only perform a single search and replace operation, the .* pattern will find the first space (since the regex engine is searching strings from left to right) and .* matches any zero or more characters (in TRE regex flavor, even including line break chars, beware when using perl=TRUE, then it is not the case) as many as possible, up to the string end.

Some variations:

sub("[[:space:]].*", "", x) # s or [[:space:]] will match more whitespace chars
sub("(*UCP)(?s)\s.*", "", x, perl=TRUE) # PCRE Unicode-aware regex
stringr::str_replace(x, "(?s) .*", "")   # (?s) will force . to match any chars

See the online R demo.