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Exercise

Getting number of levels

mutate() and summarise() in dplyr both have variants where you can add the suffix if or all to change the operation. mutate_if() and summarise_if apply their second argument, a function, to all columns where the first argument is true, and mutate_all() and summarise_all take one argument, a function, and apply it to all columns.

We'll use these along with tidyr to get the number of levels for each factor variable in multiple_choice_responses. gather() from tidyr takes a dataset from wide to long format. Its two arguments are the new column names - one contain the old column names and one all the values.

Instructions
100 XP
  • Change all the character columns to factor columns and save the new dataset as responses_as_factors.
  • Create a new dataset, number_of_levels, where you:
    • Use summarise_all to apply the function nlevels to each column.
    • Change the dataset's format from wide to long.
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