Practical Programming, 2nd Edition

Exercises

Here are some exercises for you to try on your own. Solutions are available at http://pragprog.com/titles/gwpy2/practical-programming.

1. Your lab partner claims to have written a function that replaces each value in a list with twice the preceding value (and the first value with 0). For example, if the list [1, 2, 3] is passed as an argument, the function is supposed to turn it into [0, 2, 4]. Here’s the code:

   def double_preceding(values):
       """ (list of number) -> NoneType
   
       Replace each item in the list with twice the value of the
       preceding item, and replace the first item with 0.
   
       >>> L = [1, 2, 3]
       >>> double_preceding(L)
       >>> L
       [0, 2, 4]
       """
   
   
       if values != []:
           temp = values[0]
    values[0] ...