Determining Letter Frequency Of Cipher Text
I am trying to make a tool that finds the frequencies of letters in some type of cipher text. Lets suppose it is all lowercase a-z no numbers. The encoded message is in a txt file
Solution 1:
import collections
d = collections.defaultdict(int)
for c in 'test':
d[c] += 1print d # defaultdict(<type'int'>, {'s': 1, 'e': 1, 't': 2})
From a file:
myfile = open('test.txt')
forlinein myfile:
line = line.rstrip('\n')
forcin line:
d[c] += 1
For the genius that is the defaultdict container, we must give thanks and praise. Otherwise we'd all be doing something silly like this:
s = "andnowforsomethingcompletelydifferent"
d = {}
for letter in s:
if letter not in d:
d[letter] = 1
else:
d[letter] += 1
Solution 2:
The modern way:
from collections import Counter
string = "ihavesometextbutidontmindsharing"
Counter(string)
#>>> Counter({'i': 4, 't': 4, 'e': 3, 'n': 3, 's': 2, 'h': 2, 'm': 2, 'o': 2, 'a': 2, 'd': 2, 'x': 1, 'r': 1, 'u': 1, 'b': 1, 'v': 1, 'g': 1})
Solution 3:
If you want to know the relative frequency of a letter c, you would have to divide number of occurrences of c by the length of the input.
For instance, taking Adam's example:
s = "andnowforsomethingcompletelydifferent"n = len(s) # n = 37
and storing the absolute frequence of each letter in
dict[letter]
we obtain the relative frequencies by:
from string import ascii_lowercase # this is "a...z"for c in ascii_lowercase:
print c, dict[c]/float(n)
putting it all together, we get something like this:
# get input
s = "andnowforsomethingcompletelydifferent"
n = len(s) # n = 37# get absolute frequencies of lettersimport collections
dict = collections.defaultdict(int)
for c in s:
dict[c] += 1# print relative frequenciesfrom string import ascii_lowercase # this is "a...z"for c in ascii_lowercase:
print c, dict[c]/float(n)
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