Simulates a post office

postOffice.py

"""Licensed under GPLv3 <http://www.gnu.org/licenses/>.
Authors:
Eric Lopes
"""
import random
import sys

class PostOffice:

    def __init__(self):
        self.queue = []
        self.total_leave_time_spent = 0
        self.num_customers_arrive = 0
        self.num_customers_leave_without_service = 0
        self.working_minutes = 0
        self.idle_time = 0
        self.serving_customers = []
        self.num_leaves = 0

    @property
    def total_time_spent(self):
        minute = self.working_minutes
        qtime = sum([minute-customer+1 for customer in self.queue])
        stime = sum([minute-customer+1 for customer in self.serving_customers])
        return self.total_leave_time_spent + qtime + stime 

    def work(self, minutes=60*8):
        for minute in range(minutes):
            self.working_minutes += 1
            r = random.random()
            #New costumer arrives
            if r<=0.6:
                self.num_customers_arrive += 1
                if len(self.serving_customers)<2:
                    self.serving_customers.append(minute)
                else:
                    self.queue.append(minute)

            #After arrives, check for idle clerks
            if len(self.serving_customers)<2:
                self.idle_time += 2-len(self.serving_customers)

            #Each serving customer has 25% of chance to complete their business
            for serving_customer in self.serving_customers:
                r = random.random()
                if r<=0.25:
                    self.num_leaves += 1
                    customer = self.serving_customers.pop(0)
                    self.total_leave_time_spent += minute-customer+1
                    if len(self.queue)>0:
                        new_costumer = self.queue.pop(0)
                        self.serving_customers.append(new_costumer)

            r = random.random()
            #At the end of minute, someone in line may give up and leave
            if r<=0.05 and len(self.queue)>0:
                self.num_leaves += 1
                n = random.randrange(len(self.queue))
                customer = self.queue.pop(n)
                self.num_customers_leave_without_service += 1
                self.total_leave_time_spent += minute-customer+1

if __name__== '__main__':
    n = 480
    if len(sys.argv)>1:
        n = int(sys.argv[1])
    post = PostOffice()
    post.work(n)
    print("avg time per customer", post.total_time_spent/post.num_customers_arrive)
    print("#customers arrived", post.num_customers_arrive)
    print("#cdustomers that leave without service", 
          post.num_customers_leave_without_service)
    print("%customers that leave without service", 
          100*post.num_customers_leave_without_service/post.num_customers_arrive, 
          "%")
    print("idle time", post.idle_time)
    print("%idle time", 100*post.idle_time/(2*post.working_minutes), "%")
    print("%leaves (with or without service)", 
          100*post.num_leaves/post.working_minutes, "%")
    print("working minutes", post.working_minutes)