New issue 1165: angular_momentum_vector derived quantity fails for an ORION dataset https://bitbucket.org/yt_analysis/yt/issues/1165/angular_momentum_vector-der... Nathan Goldbaum: This is a weird one. With the following dataset (spread over three files): http://use.yt/upload/5e496e7c http://use.yt/upload/99731ae6 http://use.yt/upload/ac7409e1 and the following test script: ``` #!python import yt file = "data.0100.3d.hdf5" ds = yt.load(file) sp = ds.sphere("center", (0.1, 'pc')) L = sp.quantities.angular_momentum_vector() ``` you will get the following error: ``` #!python Traceback (most recent call last): File "test.py", line 7, in <module> L = sp.quantities.angular_momentum_vector() File "/Users/goldbaum/Documents/yt-hg/yt/data_objects/derived_quantities.py", line 72, in __call__ values[i].append(storage[key][i]) IndexError: list index out of range ``` When I step through in a debugger, it seems that the `parallel_objects` inside of the `DerivedQuantity` base class is not properly combining data from the two chunks that get processed. More specifically, the `parallel_passthrough` decorator on the `par_combine_objects` method is only returning data from the first chunk, not combining data from both chunks. This is totally weird because it's very well tested, often-exercised code. I'm not terribly familiar with the internals of the parallel analysis interface and would appreciate another set of eyes here. @brittonsmith @MatthewTurk maybe?