WorldViz User Forum - about maplotlib in Vizard

Code:
import matplotlib

matplotlib.use('agg') 

import matplotlib.pyplot as plt



import time

import random



import viz

import viztask



import vizmatplot



viz.go()



#determine size of arrays (number of samples)

MAX_SIZE_OF_ARRAY = 5000



#create arrays

array_x, array_y = [],[]



#fill array with zeros 

for i in range(0,MAX_SIZE_OF_ARRAY):

        array_x.append(0)

        array_y.append(0)

        

###---matplotlib codes---###

fig = plt.figure()        #instantiate pyplot figure

ax = fig.add_subplot(111)        #create axes

ax.axis([0,MAX_SIZE_OF_ARRAY,0,1])        #determine axis limits

line, = ax.plot(array_x,array_y)        #instantiate plot 

matplot = vizmatplot.Show(fig)

matplot.showDrawRate(viz.ON)



def plotter():

        """ task that randomly creates y data while incrementing x data"""

        while True:

                #yield None

                for i in range (0,MAX_SIZE_OF_ARRAY):

                        array_x[i] = (i)        

                        array_y[i] = (random.random())        

                        ax.axis([0, MAX_SIZE_OF_ARRAY, 0, 1])        #make sure the axis limits don't change

                        line.set_data(array_x, array_y)        #set the data points

                

                        yield None        #wait at least a frame before setting new data points

                #        yield viztask.waitTime(matplot.rate) #or wait draw rate length calculated in module

                

                for b in range(0,MAX_SIZE_OF_ARRAY):        #clear out the arrays 

                        array_x[b] = 0

                        array_y[b] = 0

                        line.set_data(array_x,array_y)        #clear graph by setting all data points to [0,0]                        

        

viztask.schedule( plotter() )
this code comes out an error of "RuntimeError: dictionary changed size during iteration", anyone know how to solve it?

the code was from matplotlib website in Vizard webpage.