Extract matching patterns from a string.

Usage

re2_extract(string, pattern, anchor = UNANCHORED, parallel = FALSE, grain_size = 1e+05, ...)
re2_extract_all(string, pattern, anchor = UNANCHORED, parallel = FALSE, grain_size = 1e+05, ...)

Arguments

string

a character vector

pattern

a character vector or pre-compiled regular expressions

anchor

see UNANCHORED

parallel

use multithread

grain_size

a minimum chunk size for tuning the behavior of parallel algorithms

...

further arguments passed to re2

Examples

re2_extract("yabba dabba doo", "(.)")

[1] "y"

re2_extract_all("yabba dabba doo", "(.)")

[[1]]
 [1] "y" "a" "b" "b" "a" " " "d" "a" "b" "b" "a" " " "d" "o" "o"



str <- c("Aster", "Azalea x2", "Baby's Breath", "Bellflower")
re2_extract(str, "\\d")

[1] NA  "2" NA  NA 

re2_extract(str, "[a-z]+")

[1] "ster"      "zalea"     "aby"       "ellflower"

re2_extract(str, "\\b\\w{1,3}\\b")

[1] NA   "x2" "s"  NA  


# Extract all matches
re2_extract_all(str, "[A-Za-z]+")

[[1]]
[1] "Aster"

[[2]]
[1] "Azalea" "x"     

[[3]]
[1] "Baby"   "s"      "Breath"

[[4]]
[1] "Bellflower"


re2_extract_all(str, "\\b\\w{1,3}\\b")

[[1]]
character(0)

[[2]]
[1] "x2"

[[3]]
[1] "s"

[[4]]
character(0)


re2_extract_all(str, "\\d")

[[1]]
character(0)

[[2]]
[1] "2"

[[3]]
character(0)

[[4]]
character(0)

See also