[yt-users] Clump tracking!

[Matthew Turk]

Hi Patrick,

Thanks for writing, and welcome to yt-users.  :)

On Thu, Oct 4, 2012 at 9:42 AM, Patrick Rieser
<patrick.rieser at uibk.ac.at> wrote:
> Heya everyone!
>
> I am trying to track clumps across multiple snapshots (from flash). Now my
> questions is, has anybody done something like this and would be willing to
> share his/her code?

David Collins wrote some code that did this, a couple years ago.  I
don't know the current status.

If you wanted to write a new set of code to do this (and you didn't
want to go full-on "lagrangian coherent structures") there are some
things in yt that could help out.  For instance, we include a Cython
kD-tree that we use to provide a nearest-neighbor search when doing
merger trees.  This is used in a very simple way in the code in
yt/analysis_modules/halo_merger_tree/enzofof_merger_tree.py , where
halos are loaded into a variable called halo_kdtree.  This then gets
searched with a ball query.  You could in principle load the clumps
into the same kdtree structure, perform the search, and then apply
selection criteria for clump tracking based on that.  (Of course this
is just the first step in identifying clump motion -- but it would be
a way to reduce from N^2 searching.)

Let us know if you run into any tricks or have any successes -- this
is a pretty cool idea, and I'd love to see where it leads you!

-Matt

>
> Best Wishes,
> Patrick
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