Matplotlib.pyplot.draw() in Python

matplotlib.pyplot.draw() function redraw the current figure in Matplotlib. Unlike plt.show(), it does not block the execution of code, making it especially useful in interactive sessions, real-time visualizations where the plot needs to update dynamically without pausing the program. Example:

import matplotlib.pyplot as plt

plt.plot([1, 2, 3], [4, 5, 6])
plt.draw()
plt.pause(2)  

Output

Explanation: A simple line plot is created with plt.plot([1, 2, 3], [4, 5, 6]), connecting points (1,4), (2,5) and (3,6). plt.draw() renders the plot without blocking execution and plt.pause(2) keeps it visible for 2 seconds.

Syntax

matplotlib.pyplot.draw()

Parameter: This function does not take any arguments.

Returns: This function does not return anything. It updates/redraws the current figure in-place.

Examples

Example 1: In this example, we create a simple plot, display it with an initial title and then update the title after a pause to reflect changes without blocking execution.

import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot([1, 2, 3], [3, 2, 5])
plt.title("Initial Title")
plt.draw()
plt.pause(1)

ax.set_title("Updated Title")
plt.draw()
plt.pause(2)

Output

Explanation: The plot is first drawn with a title using plt.draw(). The title is then updated and plt.draw() is called again to reflect the change immediately.

Example 2: This example demonstrates how plt.draw() can be used in interactive mode to update the plot in each iteration of a loop with real-time data changes.

import matplotlib.pyplot as plt
import numpy as np

plt.ion()  # Turn on interactive mode
fig, ax = plt.subplots()

for i in range(5):
    ax.clear()
    x = np.linspace(0, 2*np.pi, 100)
    y = np.sin(x + i)
    ax.plot(x, y)
    ax.set_title(f"Frame {i}")
    plt.draw()
    plt.pause(0.5)

Output

Explanation: In interactive mode, the plot is cleared and redrawn with updated data in each iteration. plt.draw() reflects the updates in real-time without blocking code execution.

Example 3: Here, we rotate a 3D wireframe plot by updating the view angle in a loop using plt.draw() and plt.pause() to show animation-like behavior.

from mpl_toolkits.mplot3d import axes3d
import matplotlib.pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(111, projection ='3d')

X, Y, Z = axes3d.get_test_data(0.1)
ax.plot_wireframe(X, Y, Z, rstride = 5, 
                  cstride = 5)

for angle in range(0, 360):
    ax.view_init(30, angle)
    plt.draw()
    plt.pause(.001)
    ax.set_title('matplotlib.pyplot.draw()\
    function Example', fontweight ="bold")

Output

Explanation: A 3D wireframe plot is created and rotated using ax.view_init(30, angle). plt.draw() updates the view each frame and plt.pause(0.001) enables smooth animation with dynamic title updates.