I want to be able to analyze data with Python (Part 3)

(Part 3)

1 set of coin throws = 3 times

This wasn't in the book, but I simply changed "1 set 2 throws" to "1 set 3 throws" and changed the total from "4 throws" to "6 throws".

code

There is no commentary. The contents are the same as the previous (1) and (2).

from random import randint
from decimal import Decimal
from prettytable import PrettyTable
import numpy as np

def tossBiasedCoin():
    """ Returns 0 or 1 with 0 having 2/3 chance """
    return randint(0,2) % 2

# Make a 4x4 array
counts = [[0 for j in range(4)] for i in range(4)]

# Toss a coin many times to get counts
sampleCount = 500000
for num in range(sampleCount):    
    firstSet = [tossBiasedCoin(),tossBiasedCoin(),tossBiasedCoin()] # 0, 1, 2, 3
    secondSet = [tossBiasedCoin(),tossBiasedCoin(),tossBiasedCoin()]
    counts[sum(secondSet)][sum(firstSet)] += 1

# Conert all counts to perentage
TWOPLACES = Decimal(10) ** -2 
for i in range(4):
    for j in range(4):
        value = counts[i][j]        
        counts[i][j] = (100 * Decimal(counts[i][j])/Decimal(sampleCount)).quantize(TWOPLACES)
        print("Converted the value {} to percentage {}".format(value, counts[i][j]))

# Make summaries of number of heads.
keys = np.arange(7)
values = [counts[0][0], # 0
          counts[0][1]+counts[1][0], # 1
          counts[0][2]+counts[2][0]+counts[1][1],
          counts[0][3]+counts[1][2]+counts[2][1]+counts[3][0],
          counts[1][3]+counts[2][2]+counts[3][1],
          counts[2][3]+counts[3][2],
          counts[3][3]]
          
# Add row descriptions
counts[0].insert(0, '2nd set 0 head')
counts[1].insert(0, '2nd set 1 head')
counts[2].insert(0, '2nd set 2 heads')
counts[3].insert(0, '2nd set 3 heads')

# Create table with column descriptions, add rows, then show it.
table = PrettyTable(["", "1st set 0 head", "1st set 1 head", "1st set 2 heads", "1st set 3 heads"])
table.padding_width = 1
table.add_row(counts[0])
table.add_row(counts[1])
table.add_row(counts[2])
table.add_row(counts[3])
print table

# Draw a bar chart
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
rects = plt.bar(keys,
                 values, 
                 0.5,
                 alpha=0.4,
                 align="center", 
                 color='b')

plt.xlabel('Number of heads')
plt.ylabel('Probability (%)')
plt.title('Probabilities heads with a biased coin')
plt.xticks(keys, np.arange(7))

plt.tight_layout()
plt.show()

result

It has become more like a standard deviation.

The number of cards that can be thrown at 6 is "6 x 1/3", which means that it is easy to get 2 cards.

(Part 4) is continued.