[Kst] Plotting large datasets in real time

Matthew D Truch matt at truch.net
Sat May 2 05:36:22 CEST 2009


> I may give Dirfiles a try, but I'm not sure I like the idea of having
> a whole directory of files for each graph instead of a single file. It
> seems like this would get around most of the issues I'm having with
> CSV files though.
> 
> The logging utility is written in C and I'm free to change the logging
> format to anything. I'm using Kst 1.7.0.
> 
> Is there a better way for me to handle this scenario? If Kst isn't the
> right graphing utility to use for this task, can you suggest others
> that may work better?

Kst is certainly the right graphing utility for this task.  Plotting
live data is certainly it's forte.  Using very modest machines kst can
plot much more data than you indicate you have with ease.  

As Andrew points out, CSV files are very inefficient in this regard.  If
you don't want to write your own datasource plugin for kst, I would
suggest dirfiles.  At first it may sound strange, but it really is an
extremely efficient system (the only major caveat is if you have so many
fields being read from or written to you run out of file descriptors in
the kernel; sounds like you aren't anywhere near that).  It is used for
by us for significantly larger datasets than you describe, with great
results.  

You can certainly write dirfiles yourself (very easily), but there is
also a very good library in C as well, called getdata, which I recommend.
http://getdata.sourceforge.net/

-- 
"Things are more like they are today than they ever have been before."
--------------------------
Matthew Truch
Department of Physics and Astronomy
University of Pennsylvania
matt at truch.net
http://matt.truch.net/
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