Matplotlib.axes.Axes.draw_artist() in Python

Last Updated : 30 Apr, 2020

Matplotlib is a library in Python and it is numerical – mathematical extension for NumPy library. The Axes Class contains most of the figure elements: Axis, Tick, Line2D, Text, Polygon, etc., and sets the coordinate system. And the instances of Axes supports callbacks through a callbacks attribute.

matplotlib.axes.Axes.draw_artist() Function

The Axes.draw_artist() function in axes module of matplotlib library is used to efficiently update Axes data.

Syntax: Axes.draw_artist(self, a) Parameters: This method accepts the following parameters.

a: This parameter is the artist to be draw.

Returns: This method does not return any value.

Note: This method can only be used after an initial draw which caches the renderer. Below examples illustrate the matplotlib.axes.Axes.draw_artist() function in matplotlib.axes: Example 1:

Python3

# Implementation of matplotlib function 
from random import randint, choice
import time
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches


back_color = "black"
colors = ['red', 'green', 'blue', 'purple']
width, height = 4, 4

fig, ax = plt.subplots()
ax.set(xlim =[0, width], ylim =[0, height])

fig.canvas.draw()

def update():
    x = randint(0, width - 1)
    y = randint(0, height - 1)

    arti = mpatches.Rectangle(
        (x, y), 1, 1,
        facecolor = choice(colors),
        edgecolor = back_color
    )
    ax.add_artist(arti)

    start = time.time()
    ax.draw_artist(arti)
    fig.canvas.blit(ax.bbox)
    print("Draw at time :", time.time() - start)

timer = fig.canvas.new_timer(interval = 1)
timer.add_callback(update)
timer.start()

ax.set_title('matplotlib.axes.Axes.draw_artist()\
 function Example') 

plt.show()

Output:

Draw at time : 0.37501978874206543
Draw at time : 0.015624046325683594
Draw at time : 0.03127431869506836
Draw at time : 0.015625953674316406
Draw at time : 0.015601396560668945
Draw at time : 0.015614986419677734
........
so on...

Example 2:

Python3

# Implementation of matplotlib function 
import matplotlib.pyplot as plt
import numpy as np
import time


fig, ax = plt.subplots()
line, = ax.plot(np.random.randn(100))

tstart = time.time()
num_plots = 0
fig.canvas.draw()

while time.time()-tstart < 5:
    line.set_ydata(np.random.randn(100))
    ax.draw_artist(ax.patch)
    ax.draw_artist(line)
    num_plots += 1
    
ax.set_title('matplotlib.axes.Axes.draw_artist() \
function Example') 

plt.show()