R:how to get grep to return the match, rather than the whole string
Solution 1:
Try the stringr package:
library(stringr)
str_match(alice, ".*\\.D([0-9]+)\\.LIS.*")[, 2]
Solution 2:
You can do something like this:
pat <- ".*\\.D([0-9]+)\\.LIS.*"
sub(pat, "\\1", alice)
If you only want the subset of alice where your pattern matches, try this:
pat <- ".*\\.D([0-9]+)\\.LIS.*"
sub(pat, "\\1", alice[grepl(pat, alice)])