Dinky

gistfile1.txt

#Dataframes (of strings. Glorious strings)
foo <- data.frame(c("foo","qux","baz","quux"),c("baz","bar","foo","corge"))
bar <- data.frame(c("foo","bar","baz"),c("baz","bar","foo"))

#Retrieve the subset of foo that matches entries in bar.

See here for a very kludgy solution. You're facing a general problem here, not an R problem (meaning doing multiple sub-element matching). So there will be a few solutions.

Here is a smarter solution, but you'll need to do a bit of work to recover them in a conformable format. That part was boring so I didn't do it.

Yeah, that second one looks a lot like one of my proposed solutions (although I used ddply)