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.
This exercise is part of the course
Foundations of Functional Programming with purrr
Exercise instructions
- Load the
purrrlibrary (note the 3 Rs). - Replicate the for loop from the last exercise using
map()instead. Use the same listfilesand the same functionreadr::read_csv(). - Check the length of
all_files_purrr.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Load purrr library
library(___)
# Use map to iterate
all_files_purrr <- map(___, ___)
# Output size of list object
length(___)