It looks like I was searching for the wrong term - I wanted a particle *filter*, not a *union*. More information in this YTEP: http://ytep.readthedocs.org/en/latest/YTEPs/YTEP-0014.html I believe the text of the YTEP can readily be incorporated into the docs - I will do so once I have a working example of a particle filter. -Nathan On Thu, Apr 10, 2014 at 2:13 PM, Nathan Goldbaum wrote:

Hi all,

I'm trying to define a particle union for my dataset that represents stars formed during the simulation. The most straightforward way to accomplish this is to use a mass cut.

Does anyone have examples of how to set up a particle union? Bonus if it uses enzo data.

In return for any helpful advice anyone can give, I will add sorely needed documentation for particle unions to the 3.0 docs.

-Nathan

On Fri, Apr 11, 2014 at 9:02 AM, Britton Smith wrote:

Hi Nathan,

This is how I have used particle filters: http://paste.yt-project.org/show/4509/

I could be wrong, but my understanding is that particle filters had to be added directly to an instantiated pf as in my example. If that is the case, then this YTEP is inaccurate and should be altered.

I think you're right. I was also unable to modify the enzo frontend to include a star particle ptype based on a filter, but that might have been due to a mistake on my part. On a somewhat happier note, I was able to use a particle filter to measure the star formation rate in my simulation. The script might be generally useful for other enzo and yt-3.0 users, so I've pasted a version of it here using the IsolatedGalaxy dataset: http://paste.yt-project.org/show/4514/ For IsolatedGalaxy, this creates the following plot: [image: Inline image 1] Pretty cool, I think! To all those who came up with the particle filter API, bravo! I seriously doubt I would have been able to write a concise and understandable script in older versions of yt.

Britton

On Thu, Apr 10, 2014 at 10:47 PM, Nathan Goldbaum wrote:

...

It looks like I was searching for the wrong term - I wanted a particle *filter*, not a *union*.

More information in this YTEP: http://ytep.readthedocs.org/en/latest/YTEPs/YTEP-0014.html

I believe the text of the YTEP can readily be incorporated into the docs - I will do so once I have a working example of a particle filter.

-Nathan

On Thu, Apr 10, 2014 at 2:13 PM, Nathan Goldbaum wrote:

...

Hi all,

I'm trying to define a particle union for my dataset that represents stars formed during the simulation. The most straightforward way to accomplish this is to use a mass cut.

Does anyone have examples of how to set up a particle union? Bonus if it uses enzo data.

In return for any helpful advice anyone can give, I will add sorely needed documentation for particle unions to the 3.0 docs.

-Nathan

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