"""This module contains a code example related to
Think Python, 2nd Edition
by Allen Downey
http://thinkpython2.com
Copyright 2015 Allen Downey
License: http://creativecommons.org/licenses/by/4.0/
"""
from __future__ import print_function, division
def most_frequent(s):
"""Sorts the letters in s in reverse order of frequency.
s: string
Returns: list of letters
"""
hist = make_histogram(s)
t = []
for x, freq in hist.items():
t.append((freq, x))
t.sort(reverse=True)
res = []
for freq, x in t:
res.append(x)
return res
def make_histogram(s):
"""Make a map from letters to number of times they appear in s.
s: string
Returns: map from letter to frequency
"""
hist = {}
for x in s:
hist[x] = hist.get(x, 0) + 1
return hist
def read_file(filename):
"""Returns the contents of a file as a string."""
return open(filename).read()
if __name__ == '__main__':
string = read_file('emma.txt')
letter_seq = most_frequent(string)
for x in letter_seq:
print(x)