NOTE: RT stands for "random thoughts". This is a tradition that I
initiated in the Apache Cocoon community back in the days and I would
like to initiate it here as well now that we are reaching a fairly large
pool of talented readers.
"random thoughts" are meant as collective brainstorming sessions, where
wild ideas are exchanged and morphed into something that volunteers can
work on to contribute or simply to comment upon.
Everybody is welcome to participate with any comment they have, no
matter how off-the-wall or challenging: open mind during brainstorming
is the way to capture the innovative power of the open development
periphery.
- o -
A while ago, in order to have a way to show in brief the evolution of
the success of our project, I wrote a series of scripts that mine logs
from our development infrastructure and generate time plots out of them.
The result was named "graphical history" and spans the entire existence
of the project and can be seen at
http://simile.mit.edu/history/
The data is available at
http://simile.mit.edu/history/data/
and it's updated with a cron job every hour.
The time plots are generated using "ploticus" and saved as PNG files.
A few weeks ago, we reached the limit of how many 'datapoints' ploticus
can handle and we had to turn off the plotting stage... meaning that the
data is being updated, but the plots are not (they are lagging behind).
This whole 'graphical history' started as a quick and dirty hack and
I've added more and more functionality to it depending on internals
needs. Some of the scripts are fairly general and could be used without
change in other web sites, I've made them available at
http://simile.mit.edu/repository/stats/
including the ploticus scripts that generate the plots.
- o -
Ploticus is fast and relatively easy to use, but it is clear that it
would be way better to have more interactivity in such time charts.
Timeline was designed to show data events and time periods that were
meaningful in isolation, while time series plotting is more about
showing the variability of a particular function over time.
At the same time, it is often important to merge the two together: stock
quotes and news events, server logs and blog posts, temperature of a
patient and treatment events, speed of running and music playing on your
ipod (for those who have the nike+ipod combo)...
There are endless situations when it is very much useful to plot a
continuous (or artificially averaged to be so) time series *and* a set
of discrete events and/or time ranges.
Some of the best example of such thing is Google Finance:
http://finance.google.com/finance?q=GOOG
which is done using flash + ajax (in the latest flash there is a way to
control it directly via javascript in the web page).
- o -
So now I wonder: should we incorporate time series plotting into
Timeline or write something else entirely?
And if we incorporate it, how? and what technology should we use? flash,
canvas, svg, java?
And what features should we have? I think some sort of zooming is a must
as plots tend to exhibit different features on different scales... how
about toggling between linear and logarithmic scales?
What do you think?
--
Stefano Mazzocchi
Digital Libraries Research Group Research Scientist
Massachusetts Institute of Technology
E25-131, 77 Massachusetts Ave skype: stefanomazzocchi
Cambridge, MA 02139-4307, USA email: stefanom at mit . edu
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