remotes::install_github("ellisvalentiner/grokr")

library(grokr)

g <- grok("Hello %{WORD:name}")
g$match("Hello world!")
#> $name
#> [1] "world"

x <- c(
  "55.3.244.1 GET /index.html 15824 0.043",
  "127.0.0.1 POST /index.html 43658 1.234"
)

grok_match(
  string = x,
  pattern = "%{IP:client} %{WORD:method} %{URIPATHPARAM:request} %{NUMBER:bytes} %{NUMBER:duration}"
)
#> [[1]]
#> [[1]]$client
#> [1] "55.3.244.1"
#> 
#> [[1]]$method
#> [1] "GET"
#> 
#> [[1]]$request
#> [1] "/index.html"
#> 
#> [[1]]$bytes
#> [1] "15824"
#> 
#> [[1]]$duration
#> [1] "0.043"
#> 
#> 
#> [[2]]
#> [[2]]$client
#> [1] "127.0.0.1"
#> 
#> [[2]]$method
#> [1] "POST"
#> 
#> [[2]]$request
#> [1] "/index.html"
#> 
#> [[2]]$bytes
#> [1] "43658"
#> 
#> [[2]]$duration
#> [1] "1.234"