BrownianWithExpGrowthCode

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import random
import Tkinter

# Set up the graphics window
maxheight = 800
maxwidth = 800
window = Tkinter.Tk()
canvas = Tkinter.Canvas(window, width=maxwidth, height=maxheight, background="white")
canvas.pack()

class agent:
    def __init__(self,x1,y1):
        self.x = x1
        self.y = y1
        self.oldx = x1
        self.oldy = y1

xincr = 2
yincr = 2
popsize = 100
totalrun = 100
reproprob = 0.01

def coin(prob):
    return (random.random() < prob)


pop = []
for indiv in range(popsize):
    pop.append(agent(maxwidth/2,maxheight/2))
    canvas.create_oval(maxwidth/2,maxheight/2,2+maxwidth/2,2+maxheight/2,fill='black')

for time in range(totalrun):
    indiv = 0
    x1 = pop[indiv].x
    y1 = pop[indiv].y
    while indiv < len(pop):
        if coin(reproprob):
            pop.append(agent(x1,y1))
            canvas.create_oval(x1,y1,2+x1,2+y1,fill='black')
        if coin(0.5):
            pop[indiv].x = pop[indiv].x + xincr
        else:
            pop[indiv].x = pop[indiv].x - xincr

        if coin(0.5):
            pop[indiv].y = pop[indiv].y + yincr
        else:
            pop[indiv].y = pop[indiv].y - yincr
        canvas.coords(indiv+1,pop[indiv].x,pop[indiv].y,2+pop[indiv].x,2+pop[indiv].y)
        pop[indiv].oldx = pop[indiv].x
        pop[indiv].oldy = pop[indiv].y
        indiv = indiv + 1
    print time + 1