Intermittent statistics error in Samples

[jotaylor]

Sometimes this error occurs when using statistics.mode. Re-running SPAMM once or twice gets rid of it.

Mean acceptance fraction: 0.358
Saved pickle file 20190523_5826/model_20190523_5826.pickle.gz
Traceback (most recent call last):
  File "test_spamm.py", line 138, in <module>
    test_spamm(components=comps, n_walkers=int(args.n_walkers), n_iterations=int(args.n_iterations))
  File "test_spamm.py", line 107, in test_spamm
    n_iterations=n_iterations)
  File "/user/jotaylor/git/spamm/spamm/run_spamm.py", line 156, in spamm
    make_plots_from_pickle(pname, outdir)
  File "/user/jotaylor/git/spamm/spamm/analysis.py", line 245, in make_plots_from_pickle
    S = Samples(pname, outdir=outdir, gif=gif, last=last, step=step)
  File "/user/jotaylor/git/spamm/spamm/Samples.py", line 31, in __init__
    self._get_stats()
  File "/user/jotaylor/git/spamm/spamm/Samples.py", line 55, in _get_stats
    self.modes.append(statistics.mode(chain))
  File "/Users/jotaylor/anaconda3/envs/spamm/lib/python3.7/statistics.py", line 506, in mode
    'no unique mode; found %d equally common values' % len(table)
statistics.StatisticsError: no unique mode; found 2 equally common values