Mailman 3 July 2012 - yt-users

Projections and field parameters
by John ZuHone July 3, 2012

July 3, 2012

Hi all, Does anybody know how exactly projections work with field parameters? Suppose I have a field called "ProjectedVelocity" that takes a field parameter "axis" that chooses between the velocity components depending on the axis of projection. The code goes like this: proj = pf.h.proj(axis, "ProjectedVelocity", weight_field="DensitySquared") proj.set_field_parameter("axis", axis) But it looks like this field is being projected before the field parameter is set. Will I get the correct behavior when I do something later with the proj object, like generate an FRB? Best, John Z

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multiple projections
by Massimo Gaspari July 3, 2012

July 3, 2012

Hi guys, Is it possible to perform multiple projections with just one pf.h.proj (even with different weights)? I am currently doing something like: proj1 = pf.h.proj(axis, "Temperature", weight1) proj2 = pf.h.proj(axis, "Density", weight2) proj3 .... frb1 = FixedResolutionBuffer(proj1, (xmin, xmax, zmin, zmax), res) frb2 = FixedResolutionBuffer(proj2, (xmin, xmax, zmin, zmax), res) frb3 .... This way yt recomputes projections for each variable, which is obviously slow. Is it the only way? I have also a doubt on FixedResolutionBuffer. Is this always necessary after projection in order to access the data? Or can I access the data projected via pf.h.proj even without resampling? Thank you as always. Cheers, Max

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strange errors
by Geoffrey So July 3, 2012

July 3, 2012

I am trying to make projections and slices in the same script and an iterating over several DD datasets, but after a while I get this error pasted below, it seems that there's some hdf5 error where h5py cannot open a file. I've made sure the file exists and the script continues to run if I change the DD#### to continue where it failed. I've already modified the script so that each DD is using a new python instace intead of iterating through the files with one python call. I tried this in queue and interactive and get the same error, sometimes after many DD, but sometimes after only 1 or 2. Is this indicative of memory issue? If it is, I'm not getting the OOM messages even in interactive node. Has anyone encountered this before? I've stuck in import gc at the top and gc.collect() at the end of the script, too, but doesn't help. From G.S. Traceback (most recent call last): File "moviesGrey.py", line 35, in <module> proj = pf.h.proj(0, field, weight_field=field) File "/home/ux455076/dev-yt/lib/python2.7/site-packages/yt-2.4dev-py2.7-linux-x86_64.egg/yt/data_objects/data_containers.py", line 2001, in __init__ if self._okay_to_serialize and self.serialize: self._serialize(node_name=self._node_name) File "/home/ux455076/dev-yt/lib/python2.7/site-packages/yt-2.4dev-py2.7-linux-x86_64.egg/yt/data_objects/data_containers.py", line 970, in _serialize self._store_fields(self._key_fields, node_name, force) File "/home/ux455076/dev-yt/lib/python2.7/site-packages/yt-2.4dev-py2.7-linux-x86_64.egg/yt/data_objects/data_containers.py", line 947, in _store_fields passthrough = True) File "/home/ux455076/dev-yt/lib/python2.7/site-packages/yt-2.4dev-py2.7-linux-x86_64.egg/yt/utilities/parallel_tools/parallel_analysis_interface.py", line 241, in in_order f2(*args, **kwargs) File "/home/ux455076/dev-yt/lib/python2.7/site-packages/yt-2.4dev-py2.7-linux-x86_64.egg/yt/data_objects/hierarchy.py", line 278, in _reload_data_file self._data_file = h5py.File(self.__data_filename, self._data_mode) File "/home/ux455076/dev-yt/lib/python2.7/site-packages/h5py/_hl/files.py", line 150, in __init__ fid = make_fid(name, mode, fapl) File "/home/ux455076/dev-yt/lib/python2.7/site-packages/h5py/_hl/files.py", line 45, in make_fid fid = h5f.open(name, h5f.ACC_RDONLY, fapl=plist) File "h5f.pyx", line 70, in h5py.h5f.open (h5py/h5f.c:1618) IOError: unable to open file (File accessability: Unable to open file) Exception AttributeError: "'EnzoHierarchy' object has no attribute '_data_file'" in <bound method EnzoHierarchy.__del__ of <yt.frontends.enzo.data_structures.EnzoHierarchy object at 0x32a4d10>> ignored

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Error with derived field
by Nathan Butcher July 2, 2012

July 2, 2012

Hello, I am having trouble using a derived field with a CoveringGrid. I am making fields for dPhi/dx, dPhi/dy, dPhi/dz using the PotentialField from ENZO. The derivative fields do not get passed into the CoveringGrid and get recalculated. This leads to the derivative being zero in areas that were originally in coarse cells. Density and DivV fields were passed to the CoveringGrid properly. As a test I defined a field that was Density^2 and that was passed to the CoveringGrid properly, so I think it is a problem specific to derived fields based on the ENZO-specific PotentialField. I have included the source for my derivative functions. Thank you, Nathan Butcher

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Query
by Amol Holkundkar July 2, 2012

July 2, 2012

Dear All, How we can use yt to plot ASCII files like gnuplot. Any simple example will be really appreciated. Thanks, Regards Amol

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