[Visualpython-users] graphing dots

[Bruce S. <Bru...@nc...>]

Laney Mills wrote:

Hi Bruce,  Gary has helped me with a couple of Python questions.  Since 
you use VPython a lot, do you know how to adjust the dot size for 
vpython 2d plots.  I want to make the Mandelbrot set, which needs the 
highest resolution I can get, one pixel per dot if possible.  I think 
the control of dot size is done deep down in some library function 
called by vpython.  I was just hoping you had seen how to make that 
happen.  From within vpython, the minium dot size is much larger than 
one pixel.  Otherwise, vpython is perfect for the job.

Thanks,

Laney Mills,
College of Charleston

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I replied:

Unfortunately there isn't currently any simple way to do that. The 
module in question is graph.py (invoked by importing visual.graph), 
which I wrote (on Windows, it is in 
C:\Python24\Lib\site-packages\visual). For dots it uses a lower-case 
text "o" because a graph typically has different x and y scales, so any 
of the standard Visual objects wouldn't be dot-like, including a small 
sphere (which would typically end up being an ellipsoid).

I would however think that for something like the Mandelbrot set there's 
no good reason to use visual.graph at all; just use a standard VPython 
window and plot very small spheres (though in any case you may run into 
problems rendering a very large number of objects).

If for some reason you want to use visual.graph, you could modify it to 
plot small spheres instead of o's, since you may well have uniform axes 
(same x and y scales).

Bruce Sherwood

(And later Mills raised the possibility of using the Python Imaging 
Library, which might indeed be the appropriate tool for this project.)