Question

Write a function called missing_letters that takes a string parameter and returns a new string with all the letters of the alphabet that are not in the argument string. The letters in the returned string should be in alphabetical order. Your implementation should use a histogram from the histogram function. It should also use the global variable alphabet. It should use this global variable directly, not through an argument or a local copy. It should loop over the letters in alphabet to determine which are missing from the input parameter.

Answer 1

A string parameter and returns new string with all the letters of the alphabet that are not in the argument string. The letters in the returned string should be in alphabetical order. The implementation should uses a histogram from the histogram function

Explanation:

The below code is written in python :

alphabet = "abcdefghijklmnopqrstuvwxyz"

test_dups = ["zzz","dog","bookkeeper","subdermatoglyphic","subdermatoglyphics"]

test_miss = ["zzz","subdermatoglyphic","the quick brown fox jumps over the lazy dog"]

def histogram(s):

   d = dict()

   for c in s:

       if c not in d:

           d[c] = 1

       else:

           d[c] += 1

   return d

def has_duplicates(s):

   for v in histogram(s).values():

       if v > 1:

           return True

   return False

def test_dups_loop():

   for s in test_dups:

       print(s + ':', has_duplicates(s))

def missing_letters(s):

   r = list('abcdefghijklmnopqrstuvwxyz')

   s = s.lower()

   for c in s.lower():

       if c in r:

           r.remove(c)  # the first matching instance

   return ''.join(r)

def test_miss_loop():

   for s in test_miss:

       print(s + ':', missing_letters(s))

def main():

   test_dups_loop()

   test_miss_loop()

if __name__ == '__main__':

   main()