I suppose it might be hard to find "in", but the answer is "% in%". The search can also be difficult because it inis a reserved word in R due to its use in the iterator specification in for-loops:
subset(colors, color %in% c('Red' ,'Blue','Green') )
Cm:
?match
?'%in%'
"%" - , , @hadley dplyr -package. SQL, , , dplyr . , dplyr - SQL .