README.md

In yutannihilation/rr4r: Rust Regex for R

rr4r: Rust regex for R

rr4r is my practice to use Rust in an R package with the power of extendr. My current goal is to create the same interface to stringr’s functions using Rust’s regex crate.

Installation

remotes::install_github("yutannihilation/rr4r")

Example

rr4r_detect()

library(rr4r)

fruit <- c("apple", "banana", "pear", "pinapple", NA)

rr4r_detect(fruit, "a")
#> [1] TRUE TRUE TRUE TRUE   NA
rr4r_detect(fruit, "^a")
#> [1]  TRUE FALSE FALSE FALSE    NA
rr4r_detect(fruit, "a$")
#> [1] FALSE  TRUE FALSE FALSE    NA
rr4r_detect(fruit, "b")
#> [1] FALSE  TRUE FALSE FALSE    NA
rr4r_detect(fruit, "[aeiou]")
#> [1] TRUE TRUE TRUE TRUE   NA

rr4r_extract()

shopping_list <- c("apples x4", "bag of flour", "bag of sugar", "milk x2")

rr4r_extract(shopping_list, "\\d")
#> [1] "4" NA  NA  "2"
rr4r_extract(shopping_list, "[a-z]+")
#> [1] "apples" "bag"    "bag"    "milk"
rr4r_extract(shopping_list, "[a-z]{1,4}")
#> [1] "appl" "bag"  "bag"  "milk"
rr4r_extract(shopping_list, "\\b[a-z]{1,4}\\b")
#> [1] NA     "bag"  "bag"  "milk"

rr4r_extract() can accept i to choose which capture group to extract. This is useful when you don’t need the whole match (with stringi/stringr, you can use lookahead or lookbehind for this purpose, but Rust’s regex crate doesn’t support it for performance reason).

# Without index
rr4r_extract(c("<p>foo</p>", "<p>bar</p>"), "<p>(.*)</p>")
#> [1] "<p>foo</p>" "<p>bar</p>"

# With index
rr4r_extract(c("<p>foo</p>", "<p>bar</p>"), "<p>(.*)</p>", 1)
#> [1] "foo" "bar"

# stringr's equivalent using positive lookahead/lookbehind
stringr::str_extract(c("<p>foo</p>", "<p>bar</p>"), "(?<=<p>).*(?=</p>)")
#> [1] "foo" "bar"

rr4r_extract_all()

# Extract all matches
rr4r_extract_all(shopping_list, "[a-z]+")
#> [[1]]
#> [1] "apples" "x"     
#> 
#> [[2]]
#> [1] "bag"   "of"    "flour"
#> 
#> [[3]]
#> [1] "bag"   "of"    "sugar"
#> 
#> [[4]]
#> [1] "milk" "x"
rr4r_extract_all(shopping_list, "\\b[a-z]+\\b")
#> [[1]]
#> [1] "apples"
#> 
#> [[2]]
#> [1] "bag"   "of"    "flour"
#> 
#> [[3]]
#> [1] "bag"   "of"    "sugar"
#> 
#> [[4]]
#> [1] "milk"
rr4r_extract_all(shopping_list, "\\d")
#> [[1]]
#> [1] "4"
#> 
#> [[2]]
#> character(0)
#> 
#> [[3]]
#> character(0)
#> 
#> [[4]]
#> [1] "2"

rr4r_extract_groups()

library(dplyr, warn.conflicts = FALSE)

tibble(
  x = c("2020-01-02", "2021-12-31", "2022-08-09")
) %>% 
  mutate(
    rr4r_extract_groups(x, 
      pattern = "(?P<year>\\d{4})-(?P<month>\\d{2})-(?P<day>\\d{2})"
    )
  )
#> # A tibble: 3 x 4
#>   x          year  month day  
#>   <chr>      <chr> <chr> <chr>
#> 1 2020-01-02 2020  01    02   
#> 2 2021-12-31 2021  12    31   
#> 3 2022-08-09 2022  08    09

rr4r_replace()

fruits <- c("one apple", "two pears", "three bananas")
rr4r_replace(fruits, "[aeiou]", "-")
#> [1] "-ne apple"     "tw- pears"     "thr-e bananas"

rr4r_replace("a1", "\\D", toupper)
#> [1] "A1"

library(lubridate)
#> 
#> Attaching package: 'lubridate'
#> The following objects are masked from 'package:base':
#> 
#>     date, intersect, setdiff, union

x <- c("Today is 2020-02-02", "2021-03-30")
ptn <- "(?P<year>\\d{4})-(?P<month>\\d{2})-(?P<day>\\d{2})"

one_month_ago <- function(year, month, day) {
  d <- make_date(year, month, day) %m-% months(1)
  format(d, "%Y-%m-%d")
}

rr4r_replace(x, ptn, one_month_ago)
#> [1] "Today is 2020-01-02" "2021-02-28"

yutannihilation/rr4r documentation built on April 16, 2021, 8:40 a.m.