Animated graphs with matplotlib

Recently I have had not so much time to dedicate to my blog, however, today I had some spare time and decided to learn how to code animated graphs with Python and matplotlib.
Apparently it’s really simple, however a little bit of practice is needed, here below are three pieces of code where I coded and plotted the graph of (many) branch of parabolas, a random walk, and a simulated stock (a random walk again!).
Here is the half parabolas

	import numpy as np
	import matplotlib.pyplot as plt
	import matplotlib.animation as animation
	fig = plt.figure()
	ax1 = fig.add_subplot(1,1,1)
	x = [i for i in range(20)]
	y = [np.sqrt(i**3) for i in x]
	def animate(i):
	global x,y
	r = np.random.normal(0,1,1)
	xar = x
	yar = y + r*y
	#ax1.clear()
	ax1.plot(xar,yar,marker='o')
	ani = animation.FuncAnimation(fig,animate,interval=1000)
	plt.show()

view raw animatedGraphs1.py hosted with ❤ by GitHub

Below is the random walk and the video:

	import numpy as np
	import matplotlib.pyplot as plt
	import matplotlib.animation as animation
	fig = plt.figure()
	ax1 = fig.add_subplot(1,1,1)
	def randomWalk():
	r = np.random.normal(0,1,1)
	if r < 0:
	return -1
	elif r > 0:
	return 1
	else:
	return 0
	counter = 0
	start = [0]
	t = [0]
	def animate(i):
	global t,u,sd,counter
	x = t
	y = start
	counter += 1
	x.append(counter)
	y.append(start[counter-1] + randomWalk())
	plt.plot(x[counter-1],y[counter-1],marker='o',color="r")
	ani = animation.FuncAnimation(fig,animate,interval=1)
	plt.show()

view raw animatedGraphs2.py hosted with ❤ by GitHub

video of the random walk: https://www.youtube.com/watch?v=3pAHwt1ioz4

and finally the stock simulation:

	import numpy as np
	import matplotlib.pyplot as plt
	import matplotlib.animation as animation
	import random
	fig = plt.figure()
	ax1 = fig.add_subplot(1,1,1)
	def getNewPrice(s,mean,stdev):
	r = np.random.normal(0,1,1)
	priceToday = s + s*(mean/255+stdev/np.sqrt(225)*r)
	return priceToday
	z = np.random.normal(0,1,255)
	u = 0.1
	sd = 0.3
	counter = 0
	price = [100]
	t = [0]
	def animate(i):
	global t,u,sd,counter
	x = t
	y = price
	counter += 1
	x.append(counter)
	y.append(getNewPrice(price[counter-1],u,sd))
	ax1.clear()
	plt.plot(x,y,color="blue")
	ani = animation.FuncAnimation(fig,animate,interval=50)
	plt.show()

view raw animatedGraphs3.py hosted with ❤ by GitHub

Hope this was interesting .