optimal resolution for frb
Hi all, I've been doing FLASH runs in 2D and using yt to manipulate the data for display -- that is, I've been creating frb objects from slices (which are not really slices since the data is 2D anyways). One thing that bothers me about this is the need to specify the dimensions of the frb. For some reason 800 x 800 seems to be preferred in the yt docs, but it seems to me that there are certain optimal dimensions that depend on the grid structure. For example an frb that uses pixels the size of the smallest resolution element/cell or some integer multiple of that (of course less refined cells would be split into multiple pixels). How would one find what that grid size would be? I guess what I'd need to know is the dimensions of that most refined cell in the computational grid. How does one access the grid structure information in a dataset? Jon -- ________________________________________________________ Jonathan D. Slavin Harvard-Smithsonian CfA jslavin@cfa.harvard.edu 60 Garden Street, MS 83 phone: (617) 496-7981 Cambridge, MA 02138-1516 cell: (781) 363-0035 USA ________________________________________________________
Hi Jon, I'm on the road but I have some suggestions for this that I will send as soon as I can. Best, John John ZuHone Kavli Center for Astrophysics and Space Research Massachusetts Institute of Technology 77 Massachusetts Ave., 37-582G Cambridge, MA 02139 (w) 617-253-2354 (m) 781-708-5004 jzuhone@space.mit.edu jzuhone@gmail.com http://www.jzuhone.com
On Sep 25, 2015, at 1:18 PM, Slavin, Jonathan
wrote: Hi all,
I've been doing FLASH runs in 2D and using yt to manipulate the data for display -- that is, I've been creating frb objects from slices (which are not really slices since the data is 2D anyways). One thing that bothers me about this is the need to specify the dimensions of the frb. For some reason 800 x 800 seems to be preferred in the yt docs, but it seems to me that there are certain optimal dimensions that depend on the grid structure. For example an frb that uses pixels the size of the smallest resolution element/cell or some integer multiple of that (of course less refined cells would be split into multiple pixels). How would one find what that grid size would be? I guess what I'd need to know is the dimensions of that most refined cell in the computational grid. How does one access the grid structure information in a dataset?
Jon
-- ________________________________________________________ Jonathan D. Slavin Harvard-Smithsonian CfA jslavin@cfa.harvard.edu 60 Garden Street, MS 83 phone: (617) 496-7981 Cambridge, MA 02138-1516 cell: (781) 363-0035 USA ________________________________________________________
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
Making it easy to lock the FRB resolution to the simulation resolution or
some factor-of-two multiple would be a great improvement, and something
that would be not too hard I think. Right now you're right that it's not
very obvious how to do this. If you'd be interested in coming up with a UI
for making FRBs that are locked to the simulation resolution, I think that
would be a fun first yt project that many people would like to use.
One easy way to get the size of the smallest computational element is the
`ds.index.get_smallest_dx()` function, which will return the size of the
smallest cell width in code units. The ds.index object is the main way to
access information about the geometrical or mesh properties of a dataset.
For patch AMR datasets like FLASH, you can access the grid objects like so:
for grid in ds.index.grids:
print grid.LeftEdge, grid.RightEdge # left and right edge of the grid
in code units
print grid.ActiveDimensions # the dimensions of the grid patch (i.e.
number of zones along x, y, and z)
print grid.Level # AMR leve
print grid.Children # references to child grid objects, if any
print grid.Parent # reference to parent grid
print grid['dens'] # the on-disk gas density field
You can access any yt field on the grid object using a dictionary-like
lookup, just like any other yt data object.
-Nathan
On Fri, Sep 25, 2015 at 1:18 PM, Slavin, Jonathan
Hi all,
I've been doing FLASH runs in 2D and using yt to manipulate the data for display -- that is, I've been creating frb objects from slices (which are not really slices since the data is 2D anyways). One thing that bothers me about this is the need to specify the dimensions of the frb. For some reason 800 x 800 seems to be preferred in the yt docs, but it seems to me that there are certain optimal dimensions that depend on the grid structure. For example an frb that uses pixels the size of the smallest resolution element/cell or some integer multiple of that (of course less refined cells would be split into multiple pixels). How would one find what that grid size would be? I guess what I'd need to know is the dimensions of that most refined cell in the computational grid. How does one access the grid structure information in a dataset?
Jon
-- ________________________________________________________ Jonathan D. Slavin Harvard-Smithsonian CfA jslavin@cfa.harvard.edu 60 Garden Street, MS 83 phone: (617) 496-7981 Cambridge, MA 02138-1516 cell: (781) 363-0035 USA ________________________________________________________
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
participants (3)
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John ZuHone
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Nathan Goldbaum
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Slavin, Jonathan