Remove text after the second space

Question

I have a matrix like this (each row is a string):

m <- matrix(c("Agarista revoluta (Spreng.) Hook. f. ex Nied.", 
              "Amaioua intermedia Mart.", 
              "Baccharis reticularia DC."),, 1)

I would like to remove the text after the second space and to return:

Agarista revoluta
Amaioua intermedia
Baccharis reticularia

I tried some combinations with gsub but I did not succeed.

Can anyone help me with this?

Answer 1

You may use

x <- c("Agarista revoluta (Spreng.) Hook. f. ex Nied.", "Amaioua intermedia Mart.", "Baccharis reticularia DC.")
sub("^(\\S*\\s+\\S+).*", "\\1", x)
## => [1] "Agarista revoluta"     "Amaioua intermedia"    "Baccharis reticularia"

See the regex demo and an online R demo.

Pattern details:

• ^ - start of string
• (\\S*\\s+\\S+) - Group 1 capturing 0+ non-whitespace chars, then 1+ whitespaces, and then 1+ non-whitespaces
• .* - any 0+ chars, as many as possible (up to the end of string).

Note that in case your strings might have leading whitespace, and you do not want to count that whitespace in, you should use

sub("^\\s*(\\S+\\s+\\S+).*", "\\1", x)

See another R demo