Replace markdown bold syntax with latex code

February 3, 2022

I am struggling to construct the correct regex expression to replace markdown bold syntax (double stars) with LaTeX code using the stringr::str_replace_all() function.

For example, I have the string "**first chunk** not bold, and **bold again**", and I would like to convert it to "\textbf{first chunk} not bold, and \textbf{bold again}".

stringr::str_replace_all(
  "**first chunk** not bold, and **bold again**",
  pattern = "\\*\\*.*\\*\\*", # this probably needs to be updated 
  replacement = <what goes here?>
)
#> "\textbf{first chunk} not bold, and \textbf{bold again}"

Thank you

>Solution :

Use capture groups:

library(stringr)

str_replace_all(
  "**first chunk** not bold, and **bold again**",
  pattern = "\\*\\*(.*?)\\*\\*",
  replacement = "\\\\textbf{\\1}"
)

[1] "\\textbf{first chunk} not bold, and \\textbf{bold again}"