Submitting a Mortgage Application

Faisal Qureshi
faisal.qureshi@ontariotechu.ca
http://www.vclab.ca

Copyright information

© Faisal Qureshi

License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Acknowledgments

This example is taken from https://simpy.readthedocs.io/en/latest/examples/movie_renege.html

import random
import simpy
from typing import NamedTuple, List, Dict, Optional

def moviegoer(env, movie, num_tickets, theater):
    """A moviegoer tries to by a number of tickets (*num_tickets*) for
    a certain *movie* in a *theater*.

    If the movie becomes sold out, she leaves the theater. If she gets
    to the counter, she tries to buy a number of tickets. If not enough
    tickets are left, she argues with the teller and leaves.

    If at most one ticket is left after the moviegoer bought her
    tickets, the *sold out* event for this movie is triggered causing
    all remaining moviegoers to leave.

    """
    with theater.counter.request() as my_turn:
        # Wait until it's our turn or until the movie is sold out
        result = yield my_turn | theater.sold_out[movie]

        # Check if it's our turn or if movie is sold out
        if my_turn not in result:
            theater.num_renegers[movie] += 1
            return

        # Check if enough tickets left.
        if theater.available[movie] < num_tickets:
            # Moviegoer leaves after some discussion
            yield env.timeout(0.5)
            return

        # Buy tickets
        theater.available[movie] -= num_tickets
        if theater.available[movie] < sellout_threshold:
            # Trigger the "sold out" event for the movie
            theater.sold_out[movie].succeed()
            theater.when_sold_out[movie] = env.now
            theater.available[movie] = 0
        yield env.timeout(1)

def customer_arrivals(env, theater):
    """Create new *moviegoers* until the sim time reaches 120."""
    while True:
        yield env.timeout(random.expovariate(1 / 0.5))

        movie = random.choice(theater.movies)
        num_tickets = random.randint(1, 6)
        if theater.available[movie]:
            env.process(moviegoer(env, movie, num_tickets, theater))

class Theater(NamedTuple):
    counter: simpy.Resource
    movies: List[str]
    available: Dict[str, int]
    sold_out: Dict[str, simpy.Event]
    when_sold_out: Dict[str, Optional[float]]
    num_renegers: Dict[str, int]

seed = 42
num_tickets = 50  # Number of tickets per movie
sellout_threshold = 2  # Fewer tickets than this is a sellout
sim_time = 120  # Simulate until

random.seed(seed)
env = simpy.Environment()

# Create movie theater
movies = ['Python Unchained', 'Kill Process', 'Pulp Implementation']
theater = Theater(
    counter=simpy.Resource(env, capacity=1),
    movies=movies,
    available={movie: num_tickets for movie in movies},
    sold_out={movie: env.event() for movie in movies},
    when_sold_out={movie: None for movie in movies},
    num_renegers={movie: 0 for movie in movies},
)

env.process(customer_arrivals(env, theater))
env.run(until=sim_time)

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
Cell In[24], line 31, in moviegoer(env, movie, num_tickets, theater)
     30 theater.available[movie] -= num_tickets
---> 31 if theater.available[movie] < SELLOUT_THRESHOLD:
     32     # Trigger the "sold out" event for the movie
     33     theater.sold_out[movie].succeed()

NameError: name 'SELLOUT_THRESHOLD' is not defined

The above exception was the direct cause of the following exception:

NameError                                 Traceback (most recent call last)
Cell In[30], line 2
      1 env.process(customer_arrivals(env, theater))
----> 2 env.run(until=sim_time)

File ~/venv/sm/lib/python3.11/site-packages/simpy/core.py:246, in Environment.run(self, until)
    244 try:
    245     while True:
--> 246         self.step()
    247 except StopSimulation as exc:
    248     return exc.args[0]  # == until.value

File ~/venv/sm/lib/python3.11/site-packages/simpy/core.py:204, in Environment.step(self)
    202 exc = type(event._value)(*event._value.args)
    203 exc.__cause__ = event._value
--> 204 raise exc

NameError: name 'SELLOUT_THRESHOLD' is not defined

for movie in movies:
    if theater.sold_out[movie]:
        sellout_time = theater.when_sold_out[movie]
        num_renegers = theater.num_renegers[movie]
        print(
            f'Movie "{movie}" sold out {sellout_time:.1f} minutes '
            f'after ticket counter opening.'
        )
        print(f'  Number of people leaving queue when film sold out: {num_renegers}')

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[37], line 6
      3 sellout_time = theater.when_sold_out[movie]
      4 num_renegers = theater.num_renegers[movie]
      5 print(
----> 6     f'Movie "{movie}" sold out {sellout_time:.1f} minutes '
      7     f'after ticket counter opening.'
      8 )
      9 print(f'  Number of people leaving queue when film sold out: {num_renegers}')

TypeError: unsupported format string passed to NoneType.__format__