There are a lot of questions about matplotlib, pylab, pyplot, ipython, so I'm sorry if you're sick of seeing this asked. I'll try to be as specific as I can, because I've been looking through people's questions and looking at documentation for pyplot and pylab, and I still am not sure what I'm doing wrong. On with the code: Goal: plot a figure every .5 seconds, and update the figure as soon as the plot command is called. My attempt at coding this follows (running on ipython -pylab): import time ion() x=linspace(-1,1,51) plot(sin(x)) for i in range(10): plot([sin(i+j) for j in x]) #see ** print i time.sleep(1) print 'Done' It correctly plots each line, but not until it has exited the for loop. I have tried forcing a redraw by putting draw() where ** is, but that doesn't seem to work either. Ideally, I'd like to have it simply add each line, instead of doing a full redraw. If redrawing is required however, that's fine. Additional attempts at solving: just after ion(), tried adding hold(True) to no avail. for kicks tried show() for ** The closest answer I've found to what I'm trying to do was at http://stackoverflow.com/questions/2310851/plotting-lines-without-blocking-execution, but show() isn't doing anything. I apologize if this is a straightforward request, and I'm looking past something so obvious. For what it's worth, this came up while I was trying to convert matlab code from class to some python for my own use. The original matlab (initializations removed) which I have been trying to convert follows: for i=1:time plot(u) hold on pause(.01) for j=2:n-1 v(j)=u(j)-2*u(j-1) end v(1)= pi u=v end Any help, even if it's just "look up this_method" would be excellent, so I can at least narrow my efforts to figuring out how to use that method. If there's any more information that would be useful, let me know.