<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Hi,</div><div><br></div><div>I like the first example the best because usually the user has some idea of the volume they're interested in, such as looking for stars or tracer particles in a particular halo or searching for all of the stars in the simulation.</div><div><br></div><div>The dataspace framework is pretty cool because it removes the intensive need of searching through the *entire* particle list for only (in most cases) a handful of particles. Of course because this feature is new, we'd still have to support searching for certain particles if the dataspace doesn't exist.</div><div><br></div><div>Cheers,</div><div>John</div><br><div><div>On 10 Sep 2009, at 00:11, Britton Smith wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">I think something like the first example you gave would be the best. It's definitely more in keeping with the data_object[field] notation for getting grid data. In a very similar vein, I find it much more intuitive to think of asking for the particles or grid data associated with a particular object than say start with some larger structure for handling particles for the entire pf, and give me only the ones in some sphere or other object (this is my interpretation of the second example you gave).<br> <br>Additionally, I think particle data-space stuff you done in Enzo is great. It seems silly to have to read in an entire set of particles only to filter most of them back out, like with star particles. This will also come in handy for other people who are working with tracer particles.<br> <br>Britton<br><br><div class="gmail_quote">On Wed, Sep 9, 2009 at 8:47 PM, Matthew Turk <span dir="ltr"><<a href="mailto:matthewturk@gmail.com">matthewturk@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Hi guys,<br> <br> I've noticed several of you making commits about particles. (John,<br> Britton, looking at you guys.) In recent versions of Enzo, I stuck in<br> a dataspace supplement that pre-computes dataspaces for different<br> particle types in each grid, which should makes things really cheap to<br> read *only* star particles, or particles of a different type. I've<br> put in support for this in the yt-hg repo, but the biggest problem<br> with it was that I couldn't figure out the right way to address it --<br> so I'd like to put out there a question to you guys.<br> <br> In an ideal world, if you have some data object:<br> <br> data_obj<br> <br> what is the best way to be able to address particles of different<br> types, and only get those particles? (Let's pretend either that IO is<br> cheap, or we have the dataspace hack.)<br> <br> For instance,<br> <br> data_object.particles[type]["x"] # for instance<br> <br> or maybe,<br> <br> pf.h.particles[type].sphere(...)<br> <br> or something? What do you think? Any off-the-wall ideas?<br> <br> -Matt<br> _______________________________________________<br> Yt-dev mailing list<br> <a href="mailto:Yt-dev@lists.spacepope.org">Yt-dev@lists.spacepope.org</a><br> <a href="http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org" target="_blank">http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org</a><br> </blockquote></div><br> <span><ATT00001.txt></span></blockquote></div><br></body></html>