grep using a character vector with multiple patterns

Question

I am trying to use grep to test whether a vector of strings are present in an another vector or not, and to output the values that are present (the matching pat

Answer 1

Good answers, however don't forget about filter() from dplyr:

patterns <- c("A1", "A9", "A6")
>your_df
  FirstName Letter
1      Alex     A1
2      Alex     A6
3      Alex     A7
4       Bob     A1
5     Chris     A9
6     Chris     A6

result <- filter(your_df, grepl(paste(patterns, collapse="|"), Letter))

>result
  FirstName Letter
1      Alex     A1
2      Alex     A6
3       Bob     A1
4     Chris     A9
5     Chris     A6