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  3. Foundations of Functional Programming with purrr

Exercise

Iteration with purrr

You've made a great for loop, but it uses a lot of code to do something as simple as input a series of files into a list. This is where purrr comes in. We can do the same thing as a for loop in one line of code with purrr::map(). The function map() iterates over a list, and uses another function that can specified with the .f argument.

map() takes two arguments:

  • The first is the list over that will be iterated over
  • The second is a function that will act on each element of the list

The readr library is already loaded.

Instructions

100 XP
  • Load the purrr library (note the 3 Rs).
  • Replicate the for loop from the last exercise using map() instead. Use the same list files and the same function readr::read_csv().
  • Check the length of all_files_purrr.