Matplotlib - force display within a script

Question

This is highly related to an earlier question by another person a couple of years ago: Matplotlib - Force plot display and then return to main code

I am using Canopy 1.5.5 on MacOSX 10.8.5, with matplotlib 1.4.3.

I will need to load data, look at it, press enter to approve and move to the next dataset (and do that a few thousand times, so it's kind of critical to get this functionality). Here is my MWE:

import numpy as np
from matplotlib import pyplot as plt
plt.ion()
plt.figure() 
ind=np.arange(5)
for i in ind:
    plt.clf()
    plt.scatter(ind,ind+i) 
    plt.title('this is plot number %i' % i) 
    plt.show() 
    u=raw_input("Press any button")

The code seems to do everything EXCEPT actually showing me the plot. If I finish the script (or interrupt it), then I see the current figure.

I have tried everything from the previous answer: with and without interactive mode, with and without plt.show(block=False), every permutation of plt.draw and plt.show, and every backend on my available list.

This seems like a very basic functionality! Please tell me that this can be done. I find it weird that matplolib says here http://matplotlib.org/users/shell.html that "by default the drawing is deferred until the end of the script", but does not have suggestions on how to override the default. Please help!

Answer 1

Your example works for me (my backend is osx), although the figure window appears behind other windows at first. I needed to use alt-tab to raise it to the front.

Try starting your script with the --matplotlib option of IPython. You can select a backend or let it be auto-detected like so: ipython --matplotlib auto yourscript.py

Not sure if you now, but the raw_input function waits for you to press the return key, not just any key.

Edit:

About your last remark: this section explains how to force drawing before the end of the script. This can be done with the draw function. In interactive mode every pyplot command calls draw as well. Drawing in this context means rendering the figure by the backend.