Little eBay auction simulation using simpy.

auction.py

"""
Simulate listing items on ebay
"""
import simpy, random, math

NUMBER_OF_ITEMS = 3000           # Number of items available to be acutioned
AUCTION_DURATION = 7 * 24 * 60  # One week of minutes
SIM_TIME = AUCTION_DURATION * 3 # Number of auction durations to run the sim
REVENUE = 0                     # Running count of revenue
env = simpy.Environment()
items = simpy.Resource(env, NUMBER_OF_ITEMS)
MEDIAN_TIME_TO_LIST = 20

def list(env):
    for i in range(1, NUMBER_OF_ITEMS + 1):
        with items.request() as item:
            timeToCreateListing = int(math.floor(random.lognormvariate(0.2, 0.5) * 10))
            print("Current time: %s: Listing item %d taking %d minutes to list." % (format_time(env.now), i, timeToCreateListing))
            yield env.timeout(timeToCreateListing)
            env.process(sell(env, i))

def sell(env, item):
    global REVENUE
    price = math.floor(random.lognormvariate(2, 0.5)) * 10
    yield env.timeout(env.now + AUCTION_DURATION)
    REVENUE+=price
    print("Current time: %s: Item %d sold for $%d" % (format_time(env.now), item, price))
    print("Current time: %s: Total revenue = $%d" % (format_time(env.now), REVENUE))

## Helper functions
def minToDays(m):
    return math.floor(m / (60 * 24))
## These functions have confusing names. They return the current hour
## or minute of the day, independent of the day..
def minToHours(m):
    return math.floor(m / 60) % 24
def minToMin(m):
    return m % 60
def format_time(m):
    return "Day %d %02d:%02d" % (minToDays(env.now), minToHours(env.now), minToMin(env.now))

## Begin simulation
def main(n, d, t):
    """Run simulation with n items for d durtation per auction, for t
total time.
    """
    print("\nSimulation starting:\n")
    env.process(list(env))
    env.run(until=t)

main(NUMBER_OF_ITEMS, AUCTION_DURATION, SIM_TIME)

## Tests
assert minToDays(1440) == 1
assert minToHours(1500) == 1
assert minToMin(1501) == 1