Hi, A bigger problem.... The lastest version of yt The current version of the code is: --- a519b8754ba8 (yt) tip --- has problems with pickle. If I pickle a data set and then try and unpickle it, I see: unpickle core data --------------------------------------------------------------------------- KeyError Traceback (most recent call last) /home/tasker/yt/src/yt-hg/scripts/iyt in <module>() 338 339 #file = open('cores.pickle','rb') --> 340 allcloudcores = cPickle.load(file('cores.pickle', 'rb')) 341 file.close() 342 /home/tasker/yt/src/yt-hg/yt/data_objects/data_containers.pyc in _reconstruct_object(*args, **kwargs) 3676 else: new_args.append(arg) 3677 pfs = ParameterFileStore() -> 3678 pf = pfs.get_pf_hash(pfid) 3679 cls = getattr(pf.h, dtype) 3680 obj = cls(*new_args) /home/tasker/yt/src/yt-hg/yt/utilities/parameter_file_storage.pyc in get_pf_hash(self, hash) 106 def get_pf_hash(self, hash): 107 """ This returns a parameter file based on a hash. """ --> 108 return self._convert_pf(self._records[hash]) 109 110 def get_pf_ctid(self, ctid): KeyError: (('283b7c4d88671dbff7acf083098da6ae',), <function _reconstruct_object at 0x272c938>, ('283b7c4d88671dbff7acf083098da6ae', 'region', array([ 16., 16., 16.]), array([ 0., 0., 0.]), array([ 32., 32., 32.]), {'disk_center': array([16, 16, 16]), 'center': array([ 16., 16., 16.]), 'bulk_velocity': array([ 0., 0., 0.]), 'disk_vector': array([0, 0, 1]), 'disk_radius': array([ 0.1 , 0.1358, 0.1716, 0.2074, 0.2432, 0.279 , The fact it mentions the field parameters in the last line, might mean it's an error introduced because of the corrections to them (that I have been demanding!)? The script I have works fine (pickles and all) on yt version: --- 16e8d749a806 (yt) tip --- Elizabeth