Simpy_intro_graph

#---------------------------------------------------------------

# Scenario:      Customers visit a bank with one counter.

#                Show the number of waiting customers and

#                the time average of that number over time.

# Model:         Make the counter a Resource. Use Matplotlib

#                to plot the data.

#---------------------------------------------------------------

import pylab as p

import random as ran

## Model components --------------------------------------------

from SimPy.SimulationRT import *

class Visitor(Process):

    def visit(self,res,serveRate):

        yield request,self,res

        yield hold,self,ran.expovariate(serveRate)

        yield release,self,res

class VisitorGenerator(Process):

    def generate(self,arrRate,res,serveRate):

        while True:

            v = Visitor()

            activate(v,v.visit(res = res,serveRate = serveRate))

            yield hold,self,ran.expovariate(arrRate)

class Plotter(Process):

    def plotQ(self,tStep,res):

        moni = Monitor()

        p.ion()

        while now() < tEnd:

            yield hold,self,tStep

            moni.observe(len(res.waitQ))

            tAverage = moni.timeAverage()

            p.plot(moni.tseries(),moni.yseries(),"ro",

                   [now()],[tAverage],"b.")

            p.ylabel("nr waiting (time average = blue)")

            p.xlabel("time (hours)")

            p.title("Queuing customers. Time now = %s hours"%now())

            p.draw()

## Model --------------------------------------------------------

def bankModel(tStep,endTime,arrRate,serveRate,speed):

    res = Resource()

    initialize()

    vg=VisitorGenerator()

    activate(vg,vg.generate(arrRate = arrRate,res = res,serveRate = serveRate))

    pl=Plotter()

    activate(pl,pl.plotQ(tStep = tStep,res = res))

    simulate(until = endTime,real_time = True,rel_speed = speed)

## Experiment data ----------------------------------------------

arrRate = 10    # mean arrival rate of customers per hour

serveRate = 14  # mean service rate (customers per hour)

timeStep = 0.1  # plot update interval (simulation time units)

tEnd = 8        # run time (hours)

aniSpeed = 10   # ratio simulation time to real time

ran.seed(111777)

## Experiment and output ---------------------------------------

bankModel(tStep = timeStep,endTime = tEnd,speed = aniSpeed,

          arrRate = arrRate,serveRate = serveRate)