I am post processing some MHD simulations done with FLASH using yt (yt version 4.3.0). Initially, the simulation has no particles, but over time, we add some (sink) particles to it. I would like to use the boolean ds.particles_exist to check if a given FLASH HDF5 particle file has any particles in it or not. It works fine when there are particles, but gives a key error when there are no particles, instead of returning False. The same issue also occurs with an earlier version of yt (4.0.4). Traceback below:
In [1]: yt.__version__
Out[1]: '4.3.0'
In [4]: ds=yt.load('FLASH_part_0050')
yt : [INFO ] 2023-10-24 11:01:22,508 Parameters: current_time = 50966272658115.96
yt : [INFO ] 2023-10-24 11:01:22,508 Parameters: domain_dimensions = [1 1 1]
yt : [INFO ] 2023-10-24 11:01:22,508 Parameters: domain_left_edge = [-3.703e+18 -3.703e+18 -3.703e+18]
yt : [INFO ] 2023-10-24 11:01:22,508 Parameters: domain_right_edge = [3.703e+18 3.703e+18 3.703e+18]
yt : [INFO ] 2023-10-24 11:01:22,509 Parameters: cosmological_simulation = 0
In [5]: ds.particles_exist
yt : [INFO ] 2023-10-24 11:01:26,270 Allocating for 3 particles
Out[5]: True
In [6]: ds=yt.load('FLASH_part_0000')
yt : [INFO ] 2023-10-24 11:01:41,713 Parameters: current_time = 0.0
yt : [INFO ] 2023-10-24 11:01:41,713 Parameters: domain_dimensions = [1 1 1]
yt : [INFO ] 2023-10-24 11:01:41,714 Parameters: domain_left_edge = [-3.703e+18 -3.703e+18 -3.703e+18]
yt : [INFO ] 2023-10-24 11:01:41,714 Parameters: domain_right_edge = [3.703e+18 3.703e+18 3.703e+18]
yt : [INFO ] 2023-10-24 11:01:41,714 Parameters: cosmological_simulation = 0
In [7]: ds.particles_exist
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
Input In [7], in <cell line: 1>()
----> 1 ds.particles_exist
File ~/.local/lib/python3.9/site-packages/yt/data_objects/static_output.py:1238, in Dataset.particles_exist(self)
1236 @property
1237 def particles_exist(self):
-> 1238 for pt, f in itertools.product(self.particle_types_raw, self.field_list):
1239 if pt == f[0]:
1240 return True
File ~/.local/lib/python3.9/site-packages/yt/data_objects/static_output.py:657, in Dataset.field_list(self)
655 @property
656 def field_list(self):
--> 657 return self.index.field_list
File ~/.local/lib/python3.9/site-packages/yt/data_objects/static_output.py:606, in Dataset.index(self)
603 @property
604 def index(self):
605 if self._instantiated_index is None:
--> 606 self._instantiated_index = self._index_class(
607 self, dataset_type=self.dataset_type
608 )
609 # Now we do things that we need an instantiated index for
610 # ...first off, we create our field_info now.
611 oldsettings = np.geterr()
File ~/.local/lib/python3.9/site-packages/yt/geometry/particle_geometry_handler.py:72, in ParticleIndex.__init__(self, ds, dataset_type)
70 self.dataset = weakref.proxy(ds)
71 self.float_type = np.float64
---> 72 super().__init__(ds, dataset_type)
73 self._initialize_index()
File ~/.local/lib/python3.9/site-packages/yt/geometry/geometry_handler.py:42, in Index.__init__(self, ds, dataset_type)
39 self._setup_geometry()
41 mylog.debug("Initializing data grid data IO")
---> 42 self._setup_data_io()
44 # Note that this falls under the "geometry" object since it's
45 # potentially quite expensive, and should be done with the indexing.
46 mylog.debug("Detecting fields.")
File ~/.local/lib/python3.9/site-packages/yt/geometry/geometry_handler.py:124, in Index._setup_data_io(self)
122 if getattr(self, "io", None) is not None:
123 return
--> 124 self.io = io_registry[self.dataset_type](self.dataset)
File ~/.local/lib/python3.9/site-packages/yt/frontends/flash/io.py:224, in IOHandlerFLASHParticle.__init__(self, ds)
222 self._handle = ds._handle
223 self._particle_fields = determine_particle_fields(self._handle)
--> 224 self._position_fields = [
225 self._particle_fields[f"particle_pos{ax}"] for ax in "xyz"
226 ]
File ~/.local/lib/python3.9/site-packages/yt/frontends/flash/io.py:225, in <listcomp>(.0)
222 self._handle = ds._handle
223 self._particle_fields = determine_particle_fields(self._handle)
224 self._position_fields = [
--> 225 self._particle_fields[f"particle_pos{ax}"] for ax in "xyz"
226 ]
KeyError: 'particle_posx'
