12.2 Regex Practice Sites

As we introduce regex syntax in the next few sections, it’s a good idea to try them out yourself and to come up with your own variations. The easiest way to do this is not to work directly in R at the outset; instead, consider using an online regex practice site. I especially recommend RegExr, which has a nice documentation interface. Set the regex flavor to PCRE, as this is the variant of regular expression syntax that is closest to the ICU regex variant used by the stringr package. If you go on to Web Programming course then you can switch to the JavaScript flavor.

Bear in mind also that as we learn regex syntax, we’ll focus on the standard, language-independent syntax itself. There are some differences between this standard syntax and the way in which you would actually enter a regex pattern in R.