Add link to web page https://regex101.com/

[hsonne]

This page let's you test out regular expressions. Do we already have a chapter about the importance of regular expressions? We should.
I found this link in the DataCamp Course "Intermediate R - Practice"

[mrustl]

I think not. But in this context I also recommend to do the Datacamp course by Charlotte Wickham on String Manipulations in R. Chapters 3 and 4 both teach how to work with regexp.

A good helper R package for learning regex is rebus (which is also used in the Datacamp course!)