Implement a class that models a vending machine.
The vending machines we model shall be quite simple. They hold a single kind of drink, assume a bottle of water. They can accept money (the US, coins, but not pennies) and can dispense drinks and return change.
Solution:
# File: VendingMachine.py
#
# Create a class that models a vending machine.
#
#
# Name:
# EID:
# Email:
# Grader:
#
# On my honor, , this programming assignment is my own work
# and I have not provided this code to any other student.
import random
# CS303e Students. Complete the VendingMachine class below as
# specified in the assignment handout. Delete this comment afterwards.
"""Models a Vending Machine.
All transactions are in cents.
"""
class VendingMachine:
def __init__(self, numDrinks, price: int, capacity):
if numDrinks > capacity:
raise KeyError()
if price <= 0:
raise KeyError()
self.capacity = capacity
self.price = price
self.money: int = 0
self.numDrinks = numDrinks
def insert_money(self, money):
self.money += money
def can_dispense(self):
return self.numDrinks > 0 and self.money >= self.price
def dispense(self):
if self.numDrinks <= 0:
return 'EMPTY'
elif self.money < self.price:
return 'INSUFFICIENT FUNDS'
else:
self.money = self.money - self.price
self.numDrinks -= 1
return 'ENJOY'
def get_change(self):
money = self.money
self.money = 0
return money
def refill(self):
self.numDrinks = self.capacity
def main():
"""# Run a simulation using the Vending Machine objects."""
if input('Run simple tests? ') == 'y':
simple_tests()
stress_tests()
def simple_tests():
"""Simple operations with a single Vending Machine.
The VendingMachine has a capacity of 5 drinks, currently
has 2 drinks, and it costs 50 cents per drink.
"""
print('***** SIMPLE TESTS *****')
vend1 = VendingMachine(2, 50, 5)
vend1.insert_money(25)
vend1.insert_money(10)
vend1.insert_money(10)
print('can dispense:', vend1.can_dispense())
print('dispense:', vend1.dispense())
vend1.insert_money(10)
print('can dispense:', vend1.can_dispense())
print('dispense:', vend1.dispense())
print('can dispense:', vend1.can_dispense())
print('get change:', vend1.get_change())
print('get change:', vend1.get_change())
vend1.insert_money(100)
vend1.insert_money(25)
print('can dispense:', vend1.can_dispense())
print('dispense:', vend1.dispense())
print('can dispense:', vend1.can_dispense())
print('dispense:', vend1.dispense())
vend1.refill()
print('can dispense:', vend1.can_dispense())
print('dispense:', vend1.dispense())
print('can dispense:', vend1.can_dispense())
print('dispense:', vend1.dispense())
print('get change:', vend1.get_change())
print()
def stress_tests():
"""Run stress tests.
Given the same number of machines, the same number of operations,
and the same initial seed, output will be the same.
"""
# Get the seed, number of operations,
# and number of machines from the user.
random.seed(int(input('Enter random seed: ')))
num_operations = int(input('Enter the number of operations: '))
num_machines = int(input('Enter the number of machines: '))
print('\n***** STRESS TESTS *****')
# Create the required number of machines and run the tests.
machines = create_machines(num_machines, 10)
perform_stress_tests_ops(machines, num_operations)
def perform_stress_tests_ops(machines, num_operations):
"""# Run the actual operations for the stress tests."""
# Only allow US coins, excluding pennies!
# (We should get rid of pennies and probably nickels too!)
coins = [5, 10, 25, 50, 100]
last_coin_index = len(coins) - 1
last_machine_index = len(machines) - 1
# Pick a random operation.
# 55% chance of insert_money.
# 20% chance of can dispense.
# 21% chance of dispense. (If we dispense, there is a 80%
# chance dispense is called directly after.)
# 3% chance of get_change.
# 1% chance of refill.
for i in range(1, num_operations + 1):
print('Operation =', i)
machine_number = random.randint(0, last_machine_index)
print('Machine =', machine_number)
machine = machines[machine_number]
random_op = random.randint(1, 100)
if random_op <= 55:
coin = coins[random.randint(0, last_coin_index)]
print('Insert money, amount =', coin)
machine.insert_money(coin)
elif random_op <= 75:
print('Can dispense:', machine.can_dispense())
elif random_op <= 96:
result = machine.dispense()
print('Dispense:', result)
if result == 'ENJOY':
# Do they remember their change? 80% chance of yes.
if random.randint(1, 5) <= 4:
print('Get change, amount =', machine.get_change())
else:
print('Forgot change after dispense.')
elif random_op <= 99:
print('Get change, amount =', machine.get_change())
else:
print('Refill.')
machine.refill()
print()
def create_machines(num_machines, max_capacity):
"""Create a list with the required number of machines.
I expect num_machines > 0.
The first machine always has a price of 25, 1 drink,
and a capacity of 3.
All machines will have a price between
25 and 200 in multiples of 25.
All machines will have a capacity between 2 and max_capacity.
"""
price_multiplier = 25
machines = [VendingMachine(1, price_multiplier, 3)]
print('Machine 0: price = 25, capacity = 3, initial drinks = 1')
for i in range(1, num_machines):
price = random.randint(1, 8) * price_multiplier
capacity = random.randint(2, max_capacity)
drinks = random.randint(0, capacity)
print('Machine ', i, ': price = ', price, ', capacity = ', capacity,
', initial drinks = ', drinks, sep='')
machines.append(VendingMachine(drinks, price, capacity))
print()
return machines
main()