You are on your way to become the best (and the funniest) R-stats channel in KZfaq

In R studio, when you are entering a filename in a function like read_csv or read.csv... if you hit the key R-Studio will give you a list of the files that match what you have typed already. It will also get you a delicious, 0 calorie Tab soda.

([a-z]+)_(\d+) would be a somewhat more specific to define the regex. \d is a numeral char.