Re: [Matplotlib-users] some issues

[Darren D. <dd...@co...>]

Hi Steve,

On Wednesday 27 April 2005 1:39 pm, steve schmerler wrote:
> Hi
>
> I like MPL very much since I'm used to MATLAB and it's fantastic plotting
> features but I have 3 little issues (most likely newbie stuff :) to solve.
>
> 1.)
> To change the backend interactively the MPL homepage suggests something
> like
>
> 	import matplotlib
> 	from pylab import *
> 	matplotlib.use(<backend-name-string>)
> 	plot(...); show()
>
> But I found that whatever backend I tell MPL to use, it always uses the one
> defined in my .matplotlibrc.
>

If you saw this on the website, it is an error. (I could not find it myself.) 
You need to do 

import matplotlib
matplotlib.use(<backend-name-string>)
from pylab import *
plot(...); show()

>
> 2.)
> When I start my Python shell (IPython, WinXP) and use MPL the 1st time in
> the session
>
> 	from pylab import *
> 	plot(...); show()
>
> the plot window appears but I'm not able to type anything in the shell. I
> close the plot window and
>
> 	plot(...); show()
>
> again. From now on I'm able to type in the shell. What's up?

This is due to the interactive nature of MPL. By default, interactive mode is 
off, to improve performance in scripts. Have you looked into IPython as an 
alternative to the interactive python interpretter? (Its not really a shell, 
by the way.) If you dont want to use IPython, try this before you import 
pylab

import matplotlib
matplotlib.interactive(True)
from pylab import *

>
>
> 3.)
> I tried to plot a data set with 1024 points (shape(x) = shape(y) =
> (1024,)).
>
> 	plot(x,y)
>
> which takes about 4 seconds to build up the plot (at least with the TkAgg
> backend). This is far to slow for me. What can I do?

I'll have to defer to the MPL overlords on this one, I dont know enough to 
answer well.

-- 
Darren S. Dale

Bard Hall
Department of Materials Science and Engineering
Cornell University
Ithaca, NY. 14850

dd...@co...