apply a function to multiple elements of an object in purrr, return a character vector
{purrr}
return directories in named directory
{base}
control flow with for loop
{base}
apply a function to multiple elements of an object in purrr, return a double vector
{purrr}
divide data frame into groups in a list
{base}
apply a function to multiple elements of an object in purrr, return a list
{purrr}
apply a function to multiple elements of an object in purrr, return a data frame
{purrr}
The end!