Updating a matplotlib plot is straightforward. Create the data, the plot and update in a loop.
Setting interactive mode on is essential: plt.ion(). This controls if the figure is redrawn every draw() command. If it is False (the default), then the figure does not update itself.
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Update plot example
Copy the code below to test an interactive plot.
import matplotlib.pyplot as plt import numpy as np x = np.linspace(0, 10*np.pi, 100) y = np.sin(x) plt.ion() fig = plt.figure() ax = fig.add_subplot(111) line1, = ax.plot(x, y, 'b-') for phase in np.linspace(0, 10*np.pi, 100): line1.set_ydata(np.sin(0.5 * x + phase)) fig.canvas.draw() |
Capture of a frame of the program above
Explanation
We create the data to plot using:
x = np.linspace(0, 10*np.pi, 100) y = np.sin(x) |
Turn on interacive mode using:
plt.ion() |
Configure the plot (the ‘b-‘ indicates a blue line):
fig = plt.figure() ax = fig.add_subplot(111) line1, = ax.plot(x, y, 'b-') |
And finally update in a loop:
for phase in np.linspace(0, 10*np.pi, 100): line1.set_ydata(np.sin(0.5 * x + phase)) fig.canvas.draw() |