Search for pattern matches in a character vector.
The grep() function searches for matches to a pattern within each element of a character vector. By default, it returns the indices of matching elements. Setting value = TRUE returns the matching elements themselves instead.
grepl() is a related function that returns a logical vector indicating which elements match. Both support regular expressions and fixed string matching.
| Name | Description | Optional |
|---|---|---|
pattern |
A character string containing a regular expression to match. | No |
x |
A character vector to search in. | No |
value |
Logical. If TRUE, return the matching elements instead of indices. Defaults to FALSE. | Yes |
ignore.case |
Logical. If TRUE, pattern matching is case-insensitive. Defaults to FALSE. | Yes |
fruits <- c("apple", "banana", "cherry", "apricot")
grep("ap", fruits) # 1 4
grep("ap", fruits, value = TRUE) # "apple" "apricot"
grepl("an", fruits) # FALSE TRUE FALSE FALSE