Move _particle_mass_is_mass attribute to io handler and implement cor…

…rection function.

yt/frontends/enzo_e/data_structures.py

@@ -355,13 +355,6 @@ def _parse_parameter_file(self):
             with open(lcfn) as lf:
                 self.parameters = libconf.load(lf)
 
-            # Determine if particle masses are actually densities by the
-            # existence of the "mass_is_mass" particles parameter.
-            mass_flag = nested_dict_get(
-                self.parameters, ("Particle", "mass_is_mass"), default=None
-            )
-            self._particle_mass_is_mass = mass_flag is not None
-
             cosmo = nested_dict_get(self.parameters, ("Physics", "cosmology"))
             if cosmo is not None:
                 self.cosmological_simulation = 1

yt/frontends/enzo_e/fields.py

@@ -4,7 +4,9 @@
 from yt.fields.field_info_container import FieldInfoContainer
 from yt.fields.magnetic_field import setup_magnetic_field_aliases
 from yt.fields.particle_fields import add_union_field
-from yt.frontends.enzo_e.misc import nested_dict_get
+from yt.frontends.enzo_e.misc import \
+    get_particle_mass_correction, \
+    nested_dict_get
 
 rho_units = "code_mass / code_length**3"
 vel_units = "code_velocity"
@@ -149,12 +151,8 @@ def setup_particle_mass_field(self, ptype):
             return
 
         val = constants[names.index("mass")][2] * self.ds.mass_unit
-        if not getattr(self.ds, "_particle_mass_is_mass", False):
-            val = (
-                val
-                * (self.ds.domain_width / self.ds.domain_dimensions).prod()
-                / self.ds.length_unit**3
-            )
+        if not self.ds.index.io._particle_mass_is_mass:
+            val = val * get_particle_mass_correction(self.ds)
 
         def _pmass(field, data):
             return val * data[ptype, "particle_ones"]

yt/frontends/enzo_e/io.py

@@ -1,5 +1,8 @@
 import numpy as np
 
+from yt.frontends.enzo_e.misc import \
+    get_particle_mass_correction, \
+    nested_dict_get
 from yt.utilities.exceptions import YTException
 from yt.utilities.io_handler import BaseIOHandler
 from yt.utilities.on_demand_imports import _h5py as h5py
@@ -18,6 +21,13 @@ def __init__(self, *args, **kwargs):
             slice(self.ds.ghost_zones, -self.ds.ghost_zones),
         )
 
+        # Determine if particle masses are actually densities by the
+        # existence of the "mass_is_mass" particles parameter.
+        mass_flag = nested_dict_get(
+            self.ds.parameters, ("Particle", "mass_is_mass"), default=None
+        )
+        self._particle_mass_is_mass = mass_flag is not None
+
     def _read_field_names(self, grid):
         if grid.filename is None:
             return []
@@ -116,13 +126,8 @@ def _read_particle_fields(self, chunks, ptf, selector):
                         continue
                     for field in field_list:
                         data = np.asarray(group.get(pn % field)[()], "=f8")
-                        if field == "mass" and not getattr(
-                            self.ds, "_particle_mass_is_mass", False
-                        ):
-                            mfac = (
-                                self.ds.domain_width / self.ds.domain_dimensions
-                            ).prod() / self.ds.length_unit**3
-                            data[mask] *= mfac
+                        if field == "mass" and not self._particle_mass_is_mass:
+                            data[mask] *= get_particle_mass_correction(self.ds)
                         yield (ptype, field), data[mask]
             if f:
                 f.close()

yt/frontends/enzo_e/misc.py

@@ -121,3 +121,13 @@ def nested_dict_get(pdict, keys, default=None):
         except KeyError:
             return default
     return val
+
+def get_particle_mass_correction(ds):
+    """
+    Normalize particle masses by the root grid cell volume.
+
+    This correction is used for Enzo-E datasets where particle
+    masses are stored as densities.
+    """
+
+    return (ds.domain_width / ds.domain_dimensions).prod() / ds.length_unit**3