[FIXED] Not-bouncing ball on python plot

Issue

I want to make a animated plot about a ball. Something like the one bellow here. The problem is that i want it to not bounce in the axis, instead i want that it keeps moving in the plot but appearing on the other side like it was a mirror.

 import numpy as np 
    import matplotlib.pyplot as plt

plt.figure(1) 
plt.clf() 

plt.axis([-10,10,-10,10]) 
n=10 
pos=(20*np.random.sample(n*2)-10).reshape(n,2)  
vel=(0.3*np.random.normal(size=n*2)).reshape(n,2) 
sizes=100*np.random.sample(n)+100 

colors=np.random.sample([n,4]) 

circles=plt.scatter(pos[:,0], pos[:,1], marker='o', s=sizes, c=colors) 


for i in range(100):
    pos=pos+vel 
    bounce=abs(pos)>10 
    vel[bounce] = -vel[bounce] 
    circles.set_offsets(pos) 
    plt.draw() 
    plt.pause(0.05) 
plt.show()

Solution

One way to do this is to simply replace the line vel[bounce] = -vel[bounce] with pos[bounce]=-pos[bounce]. This will reset the position of the balls that reach the frame to the opposite edge of the frame.

Full code below:

import numpy as np 
import matplotlib.pyplot as plt

fig=plt.figure(1) 
plt.axis([-10,10,-10,10]) 
n=10 
pos=(20*np.random.sample(n*2)-10).reshape(n,2)  
vel=(0.3*np.random.normal(size=n*2)).reshape(n,2) 
sizes=100*np.random.sample(n)+100 

colors=np.random.sample([n,4]) 

circles=plt.scatter(pos[:,0], pos[:,1], marker='o', s=sizes, c=colors) 


for i in range(100):
    pos=pos+vel
    bounce=abs(pos)>10
      
    pos[bounce]=-pos[bounce]
    circles.set_offsets(pos) 
    plt.draw() 
    plt.pause(0.05)
 
plt.show()

And this is the output:

Answered By - jylls