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Everything in one call

In order to make this code even more reproducible, we are going to create a function that does it in one call. We have already provided you a skeleton for this function, now it's your turn to complete it!

In the previous exercises, we have written the process in several steps. Now, we want this to be done in just one call: we'll then write a function that takes a list of URLs, and return the names of the elements that are not reachable.

Once you have written this function, you could save it, and reuse it whenever you need to clean a list of URLs. And maybe put it into a package ;)

The urls list from the previous exercise is available in your workspace.

This exercise is part of the course

Intermediate Functional Programming with purrr

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Exercise instructions

  • Create, inside the map() call, a possibly() version of read_lines() that will otherwise return a 404.

  • Set the names of the output.

  • Use the paste() function with the collapse argument set to " " to turn each sublist into a character vector.

  • Remove the elements which are equal to 404.

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

url_tester <- function(url_list){
  url_list %>%
    # Map a version of read_lines() that otherwise returns 404
    map( ___(___, otherwise = ___) ) %>%
    # Set the names of the result
    ___( urls ) %>% 
    # paste() and collapse each element
    map(___, ___ = " ") %>%
    # Remove the 404 
    ___(___) %>%
    names() # Will return the names of the good ones
}

# Try this function on the urls object
url_tester(urls)
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