New issue 811: Pressure alias for the FLASH frontend doesn't work https://bitbucket.org/yt_analysis/yt/issue/811/pressure-alias-for-the-flash-... John ZuHone: Attempting to use the `"pressure"` alias for the FLASH `"pres"` field results in the following error, demonstrated by the following script: ``` #!python from yt.mods import * ds = load("GasSloshing/sloshing_nomag2_hdf5_plt_cnt_0100") sp = ds.sphere("c", (100,"kpc")) sp["pressure"] ``` ``` #!python ERROR: RuntimeError: Something has gone terribly wrong, _function is NullFunc [yt.fields.derived_field] astropy: [ERROR ] 2014-03-23 13:41:30,084 RuntimeError: Something has gone terribly wrong, _function is NullFunc --------------------------------------------------------------------------- RuntimeError Traceback (most recent call last) <ipython-input-4-a43a895d2820> in <module>() ----> 1 sp["pressure"] /Users/jzuhone/Source/yt-3.x/yt/data_objects/data_containers.pyc in __getitem__(self, key) 210 return self.field_data[f] 211 else: --> 212 self.get_data(f) 213 # fi.units is the unit expression string. We depend on the registry 214 # hanging off the dataset to define this unit object. /Users/jzuhone/Source/yt-3.x/yt/data_objects/data_containers.pyc in get_data(self, fields) 619 620 fields_to_generate += gen_fluids + gen_particles --> 621 self._generate_fields(fields_to_generate) 622 623 def _generate_fields(self, fields_to_generate): /Users/jzuhone/Source/yt-3.x/yt/data_objects/data_containers.pyc in _generate_fields(self, fields_to_generate) 636 fi = self.pf._get_field_info(*field) 637 try: --> 638 fd = self._generate_field(field) 639 if type(fd) == np.ndarray: 640 fd = self.pf.arr(fd, fi.units) /Users/jzuhone/Source/yt-3.x/yt/data_objects/data_containers.pyc in _generate_field(self, field) 247 tr = self._generate_particle_field(field) 248 else: --> 249 tr = self._generate_fluid_field(field) 250 if tr is None: 251 raise YTCouldNotGenerateField(field, self.pf) /Users/jzuhone/Source/yt-3.x/yt/data_objects/data_containers.pyc in _generate_fluid_field(self, field) 267 rv = self._generate_spatial_fluid(field, ngt_exception.ghost_zones) 268 else: --> 269 rv = finfo(gen_obj) 270 return rv 271 /Users/jzuhone/Source/yt-3.x/yt/fields/derived_field.pyc in __call__(self, data) 177 if self._function is NullFunc: 178 raise RuntimeError( --> 179 "Something has gone terribly wrong, _function is NullFunc") 180 with self.unit_registry(data): 181 dd = self._function(self, data) RuntimeError: Something has gone terribly wrong, _function is NullFunc ``` Responsible: jzuhone