[yt-svn] commit/yt: chummels: Merged in ngoldbaum/yt (pull request #1710)

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1 new commit in yt:

https://bitbucket.org/yt_analysis/yt/commits/14a4cacf4dfa/
Changeset:   14a4cacf4dfa
Branch:      yt
User:        chummels
Date:        2015-08-27 16:30:51+00:00
Summary:     Merged in ngoldbaum/yt (pull request #1710)

Gadget cosmology simulation unit fixes
Affected #:  2 files

diff -r 5e5edba3739c1b8c9f8ee2d32e87304bc64557bf -r 14a4cacf4dfaa1b0af3830e7d2efa1ab69db1b35 yt/data_objects/static_output.py
--- a/yt/data_objects/static_output.py
+++ b/yt/data_objects/static_output.py
@@ -683,6 +683,7 @@
         self.unit_registry.add("code_velocity", 1.0, dimensions.velocity)
         self.unit_registry.add("code_metallicity", 1.0,
                                dimensions.dimensionless)
+        self.unit_registry.add("a", 1.0, dimensions.dimensionless)
 
     def set_units(self):
         """
@@ -700,6 +701,7 @@
                 self.unit_registry.add(new_unit, self.unit_registry.lut[my_unit][0] /
                                        (1 + self.current_redshift),
                                        length, "\\rm{%s}/(1+z)" % my_unit)
+            self.unit_registry.modify('a', 1/(1+self.current_redshift))
 
         self.set_code_units()
 

diff -r 5e5edba3739c1b8c9f8ee2d32e87304bc64557bf -r 14a4cacf4dfaa1b0af3830e7d2efa1ab69db1b35 yt/frontends/gadget/data_structures.py
--- a/yt/frontends/gadget/data_structures.py
+++ b/yt/frontends/gadget/data_structures.py
@@ -108,6 +108,14 @@
             raise RuntimeError("units_override is not supported for GadgetDataset. "+
                                "Use unit_base instead.")
         super(GadgetDataset, self).__init__(filename, dataset_type)
+        if self.cosmological_simulation:
+            self.time_unit.convert_to_units('s/h')
+            self.length_unit.convert_to_units('kpccm/h')
+            self.mass_unit.convert_to_units('g/h')
+        else:
+            self.time_unit.convert_to_units('s')
+            self.length_unit.convert_to_units('kpc')
+            self.mass_unit.convert_to_units('Msun')
 
     def _setup_binary_spec(self, spec, spec_dict):
         if isinstance(spec, str):
@@ -218,12 +226,21 @@
         self.length_unit = self.quan(length_unit[0], length_unit[1])
 
         unit_base = self._unit_base or {}
+
+        if self.cosmological_simulation:
+            # see http://www.mpa-garching.mpg.de/gadget/gadget-list/0113.html
+            # for why we need to include a factor of square root of the
+            # scale factor
+            vel_units = "cm/s * sqrt(a)"
+        else:
+            vel_units = "cm/s"
+
         if "velocity" in unit_base:
             velocity_unit = unit_base["velocity"]
         elif "UnitVelocity_in_cm_per_s" in unit_base:
-            velocity_unit = (unit_base["UnitVelocity_in_cm_per_s"], "cm/s")
+            velocity_unit = (unit_base["UnitVelocity_in_cm_per_s"], vel_units)
         else:
-            velocity_unit = (1e5, "cm/s")
+            velocity_unit = (1e5, vel_units)
         velocity_unit = _fix_unit_ordering(velocity_unit)
         self.velocity_unit = self.quan(velocity_unit[0], velocity_unit[1])
 
@@ -238,10 +255,26 @@
                 mass_unit = (unit_base["UnitMass_in_g"], "g/h")
         else:
             # Sane default
-            mass_unit = (1.0, "1e10*Msun/h")
+            mass_unit = (1e10, "Msun/h")
         mass_unit = _fix_unit_ordering(mass_unit)
         self.mass_unit = self.quan(mass_unit[0], mass_unit[1])
-        self.time_unit = self.length_unit / self.velocity_unit
+        if self.cosmological_simulation:
+            # self.velocity_unit is the unit to rescale on-disk velocities, The
+            # actual internal velocity unit is really in comoving units
+            # since the time unit is derived from the internal velocity unit, we
+            # infer the internal velocity unit here and name it vel_unit
+            #
+            # see http://www.mpa-garching.mpg.de/gadget/gadget-list/0113.html
+            if 'velocity' in unit_base:
+                vel_unit = unit_base['velocity']
+            elif "UnitVelocity_in_cm_per_s" in unit_base:
+                vel_unit = (unit_base['UnitVelocity_in_cm_per_s'], 'cmcm/s')
+            else:
+                vel_unit = (1, 'kmcm/s')
+            vel_unit = self.quan(*vel_unit)
+        else:
+            vel_unit = self.velocity_unit
+        self.time_unit = self.length_unit / vel_unit
 
     @staticmethod
     def _validate_header(filename):

Repository URL: https://bitbucket.org/yt_analysis/yt/

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