On Fri, May 20, 2016 at 1:36 PM, Rasmi Elasmar <re2300@columbia.edu> wrote:
Hi all,

I'm trying to create two derived fields (one for stellar density, and one for dark matter density) based on these from yt2. I'm running yt 3.2.3, and the star_density and dm_density fields seem to have been removed. So far, the yt2 code has transferred fine, with minimal changes:
  • amrutils.CICDeposit_3() -> amrutils.CICDeposit.CICDeposit_3()
  • np.float64(data['dx']) -> np.float64(np.ravel(data['dx'])[0]
    • (data['dx'] appears to be a multidimensional array of all the same values of dx, so I'm just taking the first one -- is there a better way to do this?)
Besides those two quirks, the code runs (I'm able to add a field using ds.add_field), but I get an error when I try to access the data using ds.all_data()['star_density'] (it seems now is when the field is actually computed).

I get the following error:
<ipython-input-5-1af8fbcb718a> in _spdensity(field, data)
      1 def _spdensity(field, data):
----> 2     blank = np.zeros(data.ActiveDimensions, dtype='float64')
      3     if data['particle_position_x'].size == 0: return blank
      4     filter = data['creation_time'] > 0.0
      5     if not filter.any(): return blank
AttributeError: 'YTRegion' object has no attribute 'ActiveDimensions'


All the examples of ActiveDimensions that I saw in the docs and source accessed ActiveDimensions as a property of some grid (i.e. g.ActiveDimensions). Is there a simple way to access that from the data/YTRegion object that I'm missing? I can access ds.index.grids and take the first grid there, but ActiveDimensions differs across the grids (And when I try to do this from within _spdensity, data doesn't have an index.grids object, just fake_index (which can't access the grids)). Is there something I'm missing?


Thanks,

Rasmi

Hi Rasmi,

Rather than directly porting your scripts from yt-2, which will be a bit painful, it would be much easier to use built-in features of yt-3 to accomplish this. In particular, you want to use particle filters and deposited fields.

Here is a worked example where I construct "star" and "dark matter" particle filters for an Enzo dataset, then plot the deposited density of these two particle types.

https://gist.github.com/b13bd7a545dda6819972eaaaf81e83f8

Here's some more documentation on particle filters and deposited particle fields:

http://yt-project.org/docs/dev/analyzing/filtering.html#filtering-particle-fields
http://yt-project.org/docs/dev/analyzing/fields.html#deposited-particle-fields

Hope that's helpful,

Nathan
 

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