[chimera-dev] examples of 2-D plotting in plugins?

Eric Pettersen pett at cgl.ucsf.edu
Mon Nov 3 14:52:30 PST 2008

FYI, the last paragraph of my reply below may be of general interest  
to developers interested in plotting data...

On Oct 31, 2008, at 10:09 AM, Randy Heiland wrote:

> Hi gang,
> For one of the Chimera plugins that I now maintain, I'm considering
> eliminating the use of matplotlib and wondering if Chimera's innards
> are capable of doing what I want.  For starters, are there any
> example plugins, etc that demonstrate how one could do simple
> plotting and simple (image) contours?  In addition, I'd need to
> handle mouse events, e.g. to retrieve x,y positions on the contour
> image.

Hi Randy,
	I'm thinking that what Chimera currently provides will not be an  
adequate replacement for the capabilities of matplotlib that  
NLOPredict uses.  Aside from the basic Tk widgets themselves (the most  
salient of which is Canvas) the only relevant widgets I can think of  
is an interactive histogram widget in CGLtk.Histogram, and a basic  
line/point plotting widget available through  
Scientific.TkWidgets.TkPlotCanvas (Scientific.TkWidgets.TkPlotCanvas).
	But I think NLOPredict needs interactive contour and bar graphs.  As  
long as you can generate the contour image yourself somehow, I think  
you can pretty easily gin up an interactive contour plot using the  
Image item of Tk.Canvas.  As for the bar graph, would BLT (A User's  
Guide to Pmw.Blt) provide enough functionality if we decided to  
provide that?  It seems to provide bar charts (A complete reference to  
the Pmw.Blt plot widget).  It also might or might not be easier for  
you to provide BLT for NLOPredict as a stopgap measure.
	So the Chimera developers will be discussing possibly providing some  
kind of plotting library at our next weekly meeting.  Clearly,  
matplotlib is the "Cadillac" of plotting libraries.  And like a  
Cadillac it has the downside of large size -- probably in the range of  
60-80MB before compression.  It also has the drawback of depending on  
a lot of other packages which we would also have to include and port  
to all our supported platforms, including 64-bit versions thereof.  So  
I guess the question is whether we could get away with including  
something smaller like BLT, which we would also be able to deploy more  
quickly due to the lower effort involved, or do people really need the  
unique capabilities of matplotlib?  Anybody?


                         Eric Pettersen
                         UCSF Computer Graphics Lab

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