Exercise 8-13 Powerball Lottery: Most and Least Common Numbers
# Named constants
LOTTERY_NUMBERS = 69
# The get_all_numbers function returns a list containing the
# lottery numbers in pbnumbers.txt. The numbers appear in the
# order that they were read from the file.
def get_all_numbers():
# Open the lottery number file.
pblottery_file = open(‘pbnumbers.txt’, ‘r’)
# Read the file contents into a list.
pblottery = pblottery_file.readlines()
# Close the file.
pblottery_file.close()
# Strip the newline from each element.
for i in range(len(pblottery)):
pblottery[i] = pblottery[i].rstrip(‘\n’)
# Split each element into individual numbers, and
# store the individual numbers in a list named lotto_nums.
lotto_nums = []
for i in range(len(pblottery)):
number_set = pblottery[i].split()
for j in range(len(number_set)):
lotto_nums.append(int(number_set[j]))
# Return the lotto_nums list.
return lotto_nums
# The get_frequency function accepts a list of numbers and determines
# the freqeuncy of each item in the list. The max_value parameter
# specifies the max value that is stored in the list.
def get_frequency(number_list, max_value):
# Create a list to hold each number’s frequency. The list
# is initialized with each element set to 0.
frequency = [0] * (max_value + 1)
for i in range(len(number_list)):
# Get the next lottery number in the list.
num = number_list[i]
# Increment that number’s frequency.
frequency[num] += 1
# Return the frequency list.
return frequency
# The position_of_highest_value function returns the position of the
# highest value in num_list.
def position_of_highest_value(num_list):
highest = 0
highest_position = 0
for i in range(len(num_list)):
if num_list[i] > highest:
highest = num_list[i]
highest_position = i
return highest_position
# The most_common function accepts freq_list, and returns another
# list in which element 0 contains the position of the highest value in
# freq_list, element 1 contains the position of the 2nd highest value in
# freq_list, etc.
def most_common(freq_list):
# Make an empty list to hold the positions of the most common items.
common_sorted = []
# Make a copy of freq_list.
temp_list = []
for item in freq_list:
temp_list.append(item)
for i in range(len(temp_list)):
position = position_of_highest_value(temp_list)
common_sorted.append(position)
temp_list[position] = -1
# Return the common_sorted list.
return common_sorted
def main():
# Get a list of all the lottery numbers.
lotto_nums = get_all_numbers()
# Get each number’s frequency.
frequency = get_frequency(lotto_nums, LOTTERY_NUMBERS)
# Get a list of the most common values.
sorted_by_most_common = most_common(frequency)
# Display the 10 most common numbers.
print(’10 Most Common Numbers (Highest to Lowest)’)
print (‘—————————————–‘)
for i in range(10):
print(sorted_by_most_common[i])
# Display the 10 least common numbers.
sorted_by_most_common.reverse()
print(‘\n10 Least Common Numbers (Lowest to Highest)’)
print (‘—————————————–‘)
for i in range(1, 11):
print(sorted_by_most_common[i])
main()