Re: [Matplotlib-users] large data sets and performance

[Peter G. <pgr...@ge...>]

John:
Thanks very much for your investigative work.

>antialiased line drawing.  Without it, I can draw and save your figure
>(including python startup time, etc, etc) in 0.25s on a 2GHz Pentium
>4.  Is this in the ballpark for you, performance wise?
>  
>
yes.. yes..yes..

>My guess is: when you turn off antialiasing you'll be a whole lot
>happier.  Let me know.
>  
>
With antialiasing off, the performance is superb!.. I plot 500,000 
points in ~4-5 seconds.. The visual quality of the graphs is (naturally) 
inferior to the antialiased counterparts, but the software is now 
feasible for my purposes.

Just couple more questions:

1) Seems like setting 'lod' to true does not improve performance?  I 
would imagine it should, because it limits the amount of points used. 
What am I missing?

2) Is there any way to make the graphs look "prettier"? They really look 
quite OK but in some cases having a little more detail would be nice. Is 
it possible specify just how much antialiasing is needed? Are there any 
other "visual enchantment options" that can be set, and will not impact 
performace too much?


3) When I do:

plot1 = plot(arange(10000), arange(20000,30000))    #dummy data.. 10,000 pairs
lod, aa = False, False
set(l, 'lod', lod, 'antialiased', aa)

Do these options only apply to the current plot (ie. plot1)?
Is it possible to have a plot inside a plot with one being antialiased, 
and the other one not?
Do I have to re-set them after I call savefig()  (Will test this.. )

I have been playing around with the dpi setting a little. Is it supposed 
to change the size of the image and/or the resolution??

Thanks again.

-- 
Peter Groszkowski         Gemini Observatory
Tel: +1 808 974-2509      670 N. A'ohoku Place
Fax: +1 808 935-9235      Hilo, Hawai'i 96720, USA