How to grep a vector and return a single TRUE or FALSE?

Question

Is there a grep function in R that returns TRUE if a pattern is found anywhere in the given character vector and FALSE otherwise?

Answer 1

Perhaps you're looking for grepl()?

> grepl("is", c("This", "is", "a", "test", "isn't", "it?"))
[1]  TRUE  TRUE FALSE FALSE  TRUE FALSE

Where the first argument is the pattern you're looking for, the second argument is the vector against which you want to match, and the returned value is a Boolean vector of the same length describing whether or not the pattern was matched to each element.