Examples

In RVerbalExpressions: Create Regular Expressions Easily

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

library(RVerbalExpressions)

The goal of this vignette is to provide some basic examples that solve common regular expression tasks. The print and grepl calls are attached at the end of each chain to show the regular expression that is constructed and what it matches.

Contains two words

# find something that must contain two words
rx() %>% 
  rx_find("cat") %>% 
  rx_anything() %>% 
  rx_find("dog") %>% 
  print() %>% 
  grepl(c("cat dog", "cat", "dog"))

Between two words

# find something between two words
rx() %>% 
  rx_seek_prefix("cat") %>% 
  rx_something() %>% 
  rx_seek_suffix("dog") %>% 
  print() %>% 
  grepl(c("cat something dog", "catdog"), perl = TRUE)

Starts with word

# find something that starts with word
rx() %>% 
  rx_start_of_line() %>% 
  rx_find("cat") %>% 
  print() %>% 
  grepl(c("cat", "cat dog", "dog cat"))

Ends with word

# find something that ends with word
rx() %>% 
  rx_find("cat") %>% 
  rx_end_of_line() %>% 
  print() %>% 
  grepl(c("cat", "cat dog", "dog cat"))

Starts and end with words

# find something that starts with and ends with words
rx() %>% 
  rx_start_of_line() %>% 
  rx_find("cat") %>% 
  rx_anything() %>% 
  rx_find("dog") %>% 
  rx_end_of_line() %>% 
  print() %>% 
  grepl(c("cat", "cat dog", "dog cat"))

Case insensitive

# find something regardless of case
rx() %>% 
  rx_find("cat") %>% 
  rx_with_any_case() %>% 
  print() %>% 
  grepl(c("cat", "CAT"))

RVerbalExpressions documentation built on Nov. 6, 2019, 5:08 p.m.