[R] Check for presence of object in group of objects

[Christoph Heibl]

Dear List,

must be simple, but i got stuck on this...

I´ve been trying around for some time, but I could not find a  
straigthforward way to do this:
How can one ask if a certain object is element of a certain group of  
objects, e.g stored in a vector?

x <- c("a", "b", "c")
# is there a simple function which returns:
is "a" part of x?
TRUE
is "d" part of x?
FALSE

Thanks a lot
Christoph