Find matching elements

str_subset() returns all elements of string where there's at least one match to pattern. It's a wrapper around x[str_detect(x, pattern)], and is equivalent to grep(pattern, x, value = TRUE).

Use str_extract() to find the location of the match within each string.

Usage

str_subset(string, pattern, negate = FALSE)

Arguments

string

Input vector. Either a character vector, or something coercible to one.

pattern

Pattern to look for.

The default interpretation is a regular expression, as described in vignette("regular-expressions"). Use regex() for finer control of the matching behaviour.

Match a fixed string (i.e. by comparing only bytes), using fixed(). This is fast, but approximate. Generally, for matching human text, you'll want coll() which respects character matching rules for the specified locale.

Match character, word, line and sentence boundaries with boundary(). An empty pattern, "", is equivalent to boundary("character").

negate

If TRUE, inverts the resulting boolean vector.

Value

A character vector, usually smaller than string.

See also

grep() with argument value = TRUE, stringi::stri_subset() for the underlying implementation.

Examples

fruit <- c("apple", "banana", "pear", "pineapple")
str_subset(fruit, "a")
#> [1] "apple"     "banana"    "pear"      "pineapple"

str_subset(fruit, "^a")
#> [1] "apple"
str_subset(fruit, "a$")
#> [1] "banana"
str_subset(fruit, "b")
#> [1] "banana"
str_subset(fruit, "[aeiou]")
#> [1] "apple"     "banana"    "pear"      "pineapple"

# Elements that don't match
str_subset(fruit, "^p", negate = TRUE)
#> [1] "apple"  "banana"

# Missings never match
str_subset(c("a", NA, "b"), ".")
#> [1] "a" "b"