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Exercise

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 been pre-defined so you can begin with the instructions straight away!

Instructions

100 XP
  • Use grepl() to generate a vector of logicals that indicates whether these email addresses 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".