str_locate() returns the start and end position of the first match;
str_locate_all() returns the start and end position of each match.
Because the start and end values are inclusive, zero-length matches
(e.g. $, ^, \\b) will have an end that is smaller than start.
str_locate(string, pattern)
str_locate_all(string, pattern)Input vector. Either a character vector, or something coercible to one.
Pattern to look for.
The default interpretation is a regular expression, as described in
vignette("regular-expressions"). Use regex() for finer control of the
matching behaviour.
Match a fixed string (i.e. by comparing only bytes), using
fixed(). This is fast, but approximate. Generally,
for matching human text, you'll want coll() which
respects character matching rules for the specified locale.
Match character, word, line and sentence boundaries with
boundary(). An empty pattern, "", is equivalent to
boundary("character").
str_locate() returns an integer matrix with two columns and
one row for each element of string. The first column, start,
gives the position at the start of the match, and the second column, end,
gives the position of the end.
str_locate_all() returns a list of integer matrices with the same
length as string/pattern. The matrices have columns start and end
as above, and one row for each match.
str_extract() for a convenient way of extracting matches,
stringi::stri_locate() for the underlying implementation.
fruit <- c("apple", "banana", "pear", "pineapple")
str_locate(fruit, "$")
#> start end
#> [1,] 6 5
#> [2,] 7 6
#> [3,] 5 4
#> [4,] 10 9
str_locate(fruit, "a")
#> start end
#> [1,] 1 1
#> [2,] 2 2
#> [3,] 3 3
#> [4,] 5 5
str_locate(fruit, "e")
#> start end
#> [1,] 5 5
#> [2,] NA NA
#> [3,] 2 2
#> [4,] 4 4
str_locate(fruit, c("a", "b", "p", "p"))
#> start end
#> [1,] 1 1
#> [2,] 1 1
#> [3,] 1 1
#> [4,] 1 1
str_locate_all(fruit, "a")
#> [[1]]
#> start end
#> [1,] 1 1
#>
#> [[2]]
#> start end
#> [1,] 2 2
#> [2,] 4 4
#> [3,] 6 6
#>
#> [[3]]
#> start end
#> [1,] 3 3
#>
#> [[4]]
#> start end
#> [1,] 5 5
#>
str_locate_all(fruit, "e")
#> [[1]]
#> start end
#> [1,] 5 5
#>
#> [[2]]
#> start end
#>
#> [[3]]
#> start end
#> [1,] 2 2
#>
#> [[4]]
#> start end
#> [1,] 4 4
#> [2,] 9 9
#>
str_locate_all(fruit, c("a", "b", "p", "p"))
#> [[1]]
#> start end
#> [1,] 1 1
#>
#> [[2]]
#> start end
#> [1,] 1 1
#>
#> [[3]]
#> start end
#> [1,] 1 1
#>
#> [[4]]
#> start end
#> [1,] 1 1
#> [2,] 6 6
#> [3,] 7 7
#>
# Find location of every character
str_locate_all(fruit, "")
#> [[1]]
#> start end
#> [1,] 1 1
#> [2,] 2 2
#> [3,] 3 3
#> [4,] 4 4
#> [5,] 5 5
#>
#> [[2]]
#> start end
#> [1,] 1 1
#> [2,] 2 2
#> [3,] 3 3
#> [4,] 4 4
#> [5,] 5 5
#> [6,] 6 6
#>
#> [[3]]
#> start end
#> [1,] 1 1
#> [2,] 2 2
#> [3,] 3 3
#> [4,] 4 4
#>
#> [[4]]
#> start end
#> [1,] 1 1
#> [2,] 2 2
#> [3,] 3 3
#> [4,] 4 4
#> [5,] 5 5
#> [6,] 6 6
#> [7,] 7 7
#> [8,] 8 8
#> [9,] 9 9
#>