grepl & grep

In their most basic form, regular expressions can be used to see whether a pattern exists inside a character string or a vector of character strings. For this purpose, you can use:

grepl(), which returns TRUE when a pattern is found in the corresponding character string.
grep(), which returns a vector of indices of the character strings that contains the pattern.

Both functions need a pattern and an x argument, where pattern is the regular expression you want to match for, and the x argument is the character vector from which matches should be sought.

In this and the following exercises, you'll be querying and manipulating a character vector of email addresses! The vector emails has already been defined in the editor on the right so you can begin with the instructions straight away!

Use grepl() to generate a vector of logicals that indicates whether these email addressess contain "edu". Print the result to the output.
Do the same thing with grep(), but this time save the resulting indexes in a variable hits.
Use the variable hits to select from the emails vector only the emails that contain "edu".

Exercise

grepl & grep

Instructions