cipher.py

   1 import string
   2 import collections
   3
   4
   5 def caesar_cipher_letter(letter, shift):
   6     if letter in string.ascii_letters:
   7         if letter in string.ascii_lowercase:
   8             return chr((ord(letter) - ord('a') + shift) % 26 + ord('a'))
   9         else:
  10             new_letter = letter.lower()
  11             yolo = chr((ord(new_letter) - ord('a') + shift) % 26 + ord('a'))
  12             return yolo.upper()
  13     else:
  14         return letter
  15
  16 def caesar_decipher_letter(letter, shift):
  17     return caesar_cipher_letter(letter, -shift)
  18
  19 def caesar_cipher_message(message, shift):
  20     big_cipher = [caesar_cipher_letter(l, shift) for l in message]
  21     return ''.join(big_cipher)
  22
  23 def caesar_decipher_message(message, shift):
  24     return caesar_cipher_message(message, -shift)
  25
  26 def letter_frequencies(message):
  27     frequencies = collections.defaultdict(int)
  28     for letter in message:
  29         if letter in  string.ascii_letters:
  30             frequencies[letter.lower()]+=1
  31     return frequencies
  32