[Yt-dev] Halo Merger Tree

Stephen Skory stephenskory at yahoo.com
Thu Jan 28 08:24:10 PST 2010


Eric,

> 1. Have you run this on the light cone simulation yet?

No. If that is to happen, I'd like this tool to be shaken down a bit more before the resources are applied to that. But that's a good idea!

> 2. I don't know how to query an SQLite database, can you help me out with that?

Sure. The primary reason why I'm using a SQL database is all the big catalogs of observational (SDSS) and simulated data (Millennium) make the data publicly accessible via a SQL interface. What I've written isn't quite up to the scope of those databases, but as it is improved it can be (& more!). There are lots of examples of how to write SQL queries out there, but I'll write some examples specific to this database soon for you.

> 3. It looks like you are appending filenames to your list in the example below, 
> have you thought about using the EnzoSimulation class to call it and run it?

I haven't used that class before so I didn't even think to use it. I'll look into that, thanks for reminding me!

> 4. I also don't know about GraphViz, maybe you could help me out with that as 
> well.


Graphviz is a open-source tool that can build visualizations of relational data. It's not as pretty as you could do by hand with a professional graphics tool, but it has an easy to output flexible markup language and that's why I use it. There are Graphviz-Python packages, but the ones I can find have at least two years since last update, and would require someone to install on their Python, which most people have a hard time doing. Therefore I hard-coded the Graphviz output content into the source. If you want to change the output style and content, you can use what I wrote as a starting point.

http://graphviz.org/

 _______________________________________________________
sskory at physics.ucsd.edu o__ Stephen Skory
http://physics.ucsd.edu/~sskory/ _.>/ _Graduate Student
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