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@danong
Created February 28, 2016 23:18
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import random
if __name__ == "__main__":
# define and initialize queue variables
lambd_in = 0.5
lambd_out = 0.4
closing_time = 100
t = 0
num_arrivals = 0
num_departures = 0
n = 0
time_depart = float('inf')
time_arrive = random.expovariate(lambd_in)
departures = []
arrivals = []
overtime = 0
max_line_length = 0
while t < closing_time or n > 0:
# case 1 - arrival before next departure
if time_arrive <= time_depart and time_arrive <= closing_time:
t = time_arrive # move along to time ta
num_arrivals += 1 # one additional arrival
n += 1 # one additional customer
# generate time of next arrival
time_arrive = random.expovariate(lambd_in) + t
# generate time of departure if queue has been empty
if n == 1:
Y = random.expovariate(lambd_out)
time_depart = t + Y
arrivals.append(t)
print("Arrival ", num_arrivals, "at time ", t)
# case 2 - departure before next arrival
elif time_depart < time_arrive and time_depart <= closing_time:
# advance time to next departure
t = time_depart
# one less person in line
n -= 1
# one more person served
num_departures += 1
# if queue is empty, infinite time of next departure
if n == 0:
time_depart = float('inf')
# if queue isn't empty, generate next time of departure
else:
Y = random.expovariate(lambd_out)
time_depart = t + Y
departures.append(t)
print("Departure ", num_departures, "at time ", t)
# case 3 - next arrival/departure happens after closing time and there are people still in queue
elif min(time_arrive, time_depart) > closing_time and n > 0:
# advance time to next departure
t = time_depart
# one less person in line
n -= 1
# one more person served
num_departures += 1
# if line isn't empty, generate time of next departure
if n > 0:
Y = random.expovariate(lambd_out)
time_depart = t + Y
departures.append(t)
# print("Departure ", nd, "at time ", t)
# case 4 - next arrival/departure happens after closing time and there is nobody left in the queue
elif min(time_arrive, time_depart) > closing_time and n == 0:
# calculate overtime
overtime = max(t-closing_time, 0)
break
print("Overtime: ", overtime)
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