# largeFlips.py
# Introduction to Computation and Programming Using Python
# John V. Guttag, 3rd. ed.
# Chapter 17, Fig. 17-7

import random
import matplotlib.pyplot as plt


def flip_plot(min_exp, max_exp):
  """Assumes min_exp and max_exp positive ints; min_exp < max_exp
     Plots results of 2**min_exp to 2**max_exp coin flips"""
  ratios, diffs, x_axis = [], [], []
  for exp in range(min_exp, max_exp + 1):
    x_axis.append(2**exp)
  for num_flips in x_axis:
    num_heads = 0
    for n in range(num_flips):
      if random.choice(('H', 'T')) == 'H':
        num_heads += 1
    num_tails = num_flips - num_heads
    try:
      ratios.append(num_heads/num_tails)
      diffs.append(abs(num_heads - num_tails))
    except ZeroDivisionError:
      continue

  plt.title('Difference Between Heads and Tails')
  plt.xlabel('Number of Flips')
  plt.ylabel('Abs(#Heads - #Tails)')
  plt.xticks(rotation = 'vertical')
  plt.plot(x_axis, diffs, 'ko')
  plt.semilogx()
  plt.semilogy()

  plt.figure()
  plt.title('Heads/Tails Ratios')
  plt.xlabel('Number of Flips')
  plt.ylabel('#Heads/#Tails')
  plt.xticks(rotation = 'vertical')
  plt.plot(x_axis, ratios, 'ko')
  plt.semilogx()

  plt.show()


random.seed(0)
flip_plot(4, 20)