L14Q4_FrequencyAnalysis.py

# 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.

import string
alphabet = list(string.ascii_lowercase)

def freq_analysis(message):
    freq_list = []
    for i in alphabet:
        freq = float(message.count(i))/len(message)
        freq_list.append(freq)

    return freq_list



#Tests

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

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

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