Exercises
- Find a freely available government dataset on the web. Read the dataset's description, and think about what assumptions you might make about the data when planning a certain analysis. Translate these into actual code so that R can check them for you. Were there any deviations from your expectations?
- An ISBN-10 is a unique identifier for books. It is 10 characters long. The last digit is called a check digit and is determinable from the preceding digits using modular arithmetic. When the check digit is "10", it is represented with an "X". To review, an ISBN-10 is either 10 digits or nine digits, with an "X" at the end. Write a function that uses regular expressions to check if an input string (or vector of strings) is in the forma
t of a valid ISBN-10. As a bonus, write code to check if the check digit matches what it is supposed to be after learning about how the check digit is computed on Wikipedia! Use this predicate function in an assertr construct, like
lib %>% assert(YOUR_FUNCTION_HERE...