Matplotlib runs out of memory when plotting in a loop

Question

I have a fairly simple plotting routine that looks like this:

from __future__ import division
import datetime
import matplotlib
matplotlib.use(\'Agg\')
from          


        

Answer 1

Is each loop supposed to generate a new figure? I don't see you closing it or creating a new figure instance from loop to loop.

This call will clear the current figure after you save it at the end of the loop:

pyplot.clf()

I'd refactor, though, and make your code more OO and create a new figure instance on each loop:

from matplotlib import pyplot

while True:
  fig = pyplot.figure()
  ax = fig.add_subplot(111)
  ax.plot(x,y)
  ax.legend(legendStrings, loc = 'best')
  fig.savefig('himom.png')
  # etc....

Answer 2

I've also run into this error. what seems to have fixed it is

while True:
    fig = pyplot.figure()
    ax = fig.add_subplot(111)
    ax.plot(x,y)
    ax.legend(legendStrings, loc = 'best')
    fig.savefig('himom.png')
    #new bit here
    pylab.close(fig) #where f is the figure

running my loop stably now with fluctuating memory but no consistant increase

Answer 3

Answer from ninjasmith worked for me too - pyplot.close() enabled my loops to work.

From the pyplot tutorial, Working with multiple figures and axes:

You can clear the current figure with clf() and the current axes with cla(). If you find this statefulness, annoying, don’t despair, this is just a thin stateful wrapper around an object oriented API, which you can use instead (see Artist tutorial)

If you are making a long sequence of figures, you need to be aware of one more thing: the memory required for a figure is not completely released until the figure is explicitly closed with close(). Deleting all references to the figure, and/or using the window manager to kill the window in which the figure appears on the screen, is not enough, because pyplot maintains internal references until close() is called.