# Crypto Analysis: Frequency Analysis
#
# To analyze encrypted messages, to find out information about the possible 
# algorithm or even language of the clear text message, one could perform 
# frequency analysis. This process could be described as simply counting 
# the number of times a certain symbol occurs in the given text. 
# For example:
# For the text "test" the frequency of 'e' is 1, 's' is 1 and 't' is 2.
#
# The input to the function will be an encrypted body of text that only contains 
# the lowercase letters a-z. 
# As output you should return a list of the normalized frequency 
# for each of the letters a-z. 
# The normalized frequency is simply the number of occurrences, i, 
# divided by the total number of characters in the message, n.
from string import ascii_lowercase
from collections import Counter

def freq_analysis(message):
    counter = Counter(message)
    alphabet = list(ascii_lowercase)
    n = 1.0 * len(message)
    freqlist = []
    for letter in alphabet:
        freqlist.append(counter[letter]/n)
    return freqlist
      
#Tests

print freq_analysis("abcd")
#>>> [0.25, 0.25, 0.25, 0.25, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

print freq_analysis("adca")
#>>> [0.5, 0.0, 0.25, 0.25, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

print freq_analysis('bewarethebunnies')
#>>> [0.0625, 0.125, 0.0, 0.0, 0.25, 0.0, 0.0, 0.0625, 0.0625, 0.0, 0.0, 0.0, 0.0, 0.125, 0.0, 0.0, 0.0, 0.0625, 0.0625, 0.0625, 0.0625, 0.0, 0.0625, 0.0, 0.0, 0.0]
