Re-initialize the plot in pylab

Question

I am new to using PyLab. I want to plot some points. But I don't want to show the previous points ie as a new point comes the previous plotted point will vanish and the new point will be plotted. I have searched a lot but I could not find how to re-initialize the plot in between. The problem I am facing is I can set the current figure by using plt.figure(f1.number) but after plotting the point in that figure it gets permanently changed.

Answer 1

plt.hold(False) before you start plotting will do what you want.

hold determines of old artists are held-on to when new ones are plotted. The default is for hold to be on.

ex

# two lines 
plt.figure()
plt.hold(True)
plt.plot(range(5))
plt.plot(range(5)[::-1])

#one line
plt.figure()
plt.hold(False)
plt.plot(range(5))
plt.plot(range(5)[::-1])

Changing it via plt.hold changes it for all (new) axes. You can change the hold state for an individual axes by

ax = gca()
ax.hold(True)

Answer 2

With pylab, pylab.clf() should clear the figure, after which you can redraw the plot.

Alternatively, you can update your data with set_xdata and set_ydata that are methods on the axes object that gets returned when you create a new plot (either with pylab.plot or pylab.subplot ).

The latter is probably preferred, but requires a litte more work. One example I can quickly find is another SO question .