RVerbalExpressions

The goal of RVerbalExpressions is to make it easier to construct regular expressions using grammar and functionality inspired by VerbalExpressions. Usage of %>% is encouraged to build expressions in a chain like fashion.

There are a couple of functions missing from the original JSVerbalExpressions:

1. replace isn’t included because there are numerous R functions for this, gsub being one example
2. add is a utility function for appending expressions to one another and isn’t included because we use %>% for that
3. then is not included because the pipe %>% is often pronounced “then” and rx_find provides the same functionality
4. any is not included because it collides with base::any() and rx_any_of provides the same functionality

Others just haven’t made it yet, see here.

# install.packages("devtools")
devtools::install_github("VerbalExpressions/RVerbalExpressions")

library(RVerbalExpressions)

# construct an expression
x <- rx_start_of_line() %>% 
  rx_find('http') %>% 
  rx_maybe('s') %>% 
  rx_find('://') %>% 
  rx_maybe('www.') %>% 
  rx_anything_but(' ') %>% 
  rx_end_of_line()

x
#> [1] "^(?:http)(?:s)?(?:\\://)(?:www\\.)?(?:[^ ]*)$"

grepl(x, "https://www.google.com")
#> [1] TRUE