Animating moving square in python

Question

I'm new to python's matplotlib, and i want to animate a 1x1 square that moves diagonally across a grid space. I have written this bit of code that almost does what i want it to do, but the previous positions of the rectangle are still visible.

import matplotlib.pyplot as plt
import matplotlib.animation
import numpy as np

from matplotlib.patches import Rectangle


moving_block = [[0,0],[1,1],[2,2],[3,3],[4,4],[5,5]]

fig, ax = plt.subplots()

#set gridlines and lines every one unit
ax.grid(which='both')
ax.axis([0,5,0,5])


rectangle = Rectangle(moving_block[0], 1,1)
ax.add_patch(rectangle)

def animate(i):
    ax.add_patch(Rectangle(moving_block[i], 1,1))

ani = matplotlib.animation.FuncAnimation(fig, animate, 
                frames=len(moving_block), interval=300, repeat=True) 

plt.show()

How can i make only the current rectangle visible? Should i be using something other than this ax.add_patch(Rectangle) function?

Answer 1

Added cleaning "ax", at each iteration in the function "animate". If you are satisfied with the answer, do not forget to vote for it :-)

import matplotlib.pyplot as plt
import matplotlib.animation
from matplotlib.patches import Rectangle

moving_block = [[0,0],[1,1],[2,2],[3,3],[4,4],[5,5]]

fig, ax = plt.subplots()
#set gridlines and lines every one unit
ax.grid(which='both')
ax.axis([0, 5, 0, 5])

rectangle = Rectangle(moving_block[0], 1,1)
ax.add_patch(rectangle)

def animate(i):
    ax.clear()
    ax.axis([0, 5, 0, 5])
    ax.grid(which='both')
    ax.add_patch(Rectangle(moving_block[i], 1,1))


ani = matplotlib.animation.FuncAnimation(fig, animate,
                frames=len(moving_block), interval=300, repeat=True)

plt.show()