New issue 850: ParticleTrajectories fails with weakly-referenced object no longer exists https://bitbucket.org/yt_analysis/yt/issue/850/particletrajectories-fails-wi... Kacper Kowalik: Following script: ``` #!python from yt.analysis_modules.particle_trajectories.api import \ ParticleTrajectories my_fns = ["enzo_tiny_cosmology/DD%4.4i/DD%4.4i.hierarchy" % (i, i) for i in range(40)] trajs = ParticleTrajectories(my_fns, [596]) ``` fails with: ``` #!text Traceback (most recent call last): File "bug.py", line 6, in <module> trajs = ParticleTrajectories(my_fns, [596]) File "yt/analysis_modules/particle_trajectories/particle_trajectories.py", line 124, in __init__ self._get_data(field) File "yt/analysis_modules/particle_trajectories/particle_trajectories.py", line 205, in _get_data fd = dd_first._determine_fields(field)[0] File "yt/data_objects/data_containers.py", line 464, in _determine_fields finfo = self.pf._get_field_info("unknown", fname) ReferenceError: weakly-referenced object no longer exists ``` I'm currently on `1bf2d3688801 (yt-3.0) tip`