Bewildered graphs

[Tim Churches]

On Sat, 2003-07-05 at 22:07, Mark Fenbers wrote:
> I am investigating Python for the sake of ultimately generating hydrographs
> (such as this: http://ahps.erh.noaa.gov/iln/ahps/RiverDat/gifs/prgo1.png)
> on-the-fly from a web server cluster.  I have not used Python previously and do
> not yet know if Python is very useful for this or if I am wasting my time.
> 
> Quite frankly, I am a little bewildered.  Not only is there Python, but there
> are many extention modules which cloud up my view as to what I will need.
> There's Scientific Python, which sounds promising, but there's also SciPy which
> in itself has gnuplot, xplt and plt modules.  I know enough about gnuplot to
> know that it won't meet my needs because I need to be able to shade regions
> above certain values such as done in yellow on the example hydrograph (the link
> above).  It also doesn't have many font options or the ability to place an image
> such as the NOAA logo.
> 
> Can someone kindly guide me as to what I would most likely need to replicate the
> graph shown via the link above?

There are indeed many options. But you might want to have a look at the
delightfully named Ploticus (starring Russell Crowe...) at
http://ploticus.sourceforge.net/doc/Welcome.html

There is no Python interface for it, but Python is an ideal tool for
building Ploticus scripts on-the-fly and running Ploticus to create the
graphs on the Web server.

However, Ploticus has recently become available as a callable library
(libploticus) with a very simple C API which is just crying out for a
Python wrapper - and a set of Python classes to abstract the interface
on top of that. I would be happy to contribute to such a project, but am
not able to undertake the construction of a C language wrapper.

If you also need statistical analysis, I can recommend RPy (see
http://rpy.sf.net) which embeds the R statistical package in Python. R
does very, very nice graphics in all sorts of styles (see
http://www.r-project.org), although it can be overkill for some Web
server applications. Ploticus is very lightweight by comparison.

-- 

Tim C

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