"""This module contains code from

Think Python by Allen B. Downey

http://thinkpython.com

Copyright 2012 Allen B. Downey

License: GNU GPLv3 http://www.gnu.org/licenses/gpl.html

"""

import sys

import string

import matplotlib.pyplot as pyplot

from analyze_book import *

def rank_freq(hist):

"""Returns a list of tuples where each tuple is a rank

and the number of times the item with that rank appeared.

"""

# sort the list of frequencies in decreasing order

freqs = hist.values()

freqs.sort(reverse=True)

# enumerate the ranks and frequencies

rf = [(r+1, f) for r, f in enumerate(freqs)]

return rf

def print_ranks(hist):

"""Prints the rank vs. frequency data."""

for r, f in rank_freq(hist):

print r, f

def plot_ranks(hist, scale='log'):

"""Plots frequency vs. rank."""

t = rank_freq(hist)

rs, fs = zip(*t)

pyplot.clf()

pyplot.xscale(scale)

pyplot.yscale(scale)

pyplot.title('Zipf plot')

pyplot.xlabel('rank')

pyplot.ylabel('frequency')

pyplot.plot(rs, fs, 'r-')

pyplot.show()

def main(name, filename='emma.txt', flag='plot', *args):

hist = process_file(filename, skip_header=True)

# either print the results or plot them

if flag == 'print':

print_ranks(hist)

elif flag == 'plot':

plot_ranks(hist)

else:

print 'Usage: zipf.py filename [print|plot]'

if __name__ == '__main__':

main(*sys.argv)