Removing multiple spaces and trailing spaces using gsub

Question

How can I remove multiple spaces and trailing spaces using only 1 gsub? I already made this function trim <- function(x) gsub(\' {2,}\',\' \',gsub(\'^ *| *$\',\'\',

Answer 1

Use a positive lookbehind to see if the current space is preceded by a space:

^ *|(?<= ) | *$

See it here in action: http://regex101.com/r/bJ1mU0