progress bar

[robbertmijn]

Include progress bar when doing cluster based permutation tests.
Using tqdm (which should come with MNE)

[smathot]

Thanks! A progress bar is useful, but it should not print anything to the standard output by default, and the behavior should also be consistent between functions. So I would accept a revised PR if:

• The progress bar is only shown when specified through a keyword that this is necessary
• tqdm is only imported when the progress bar is shown
• All time-consuming functions show a progress bar

[robbertmijn]

Progbar is now by default disabled and is only imported and used when progbar=True is passed to lmer_series or lmer_permutation_test (not sure if there are other time consuming functions that would benefit from this)

[robbertmijn]

ps. do you think this is the part where it might be helpful to build in the possibility for multiprocessing? That would drastically speed up the permutation tests (which now take many hours).

[smathot]

This looks almost good, but it is not complete. Things to do:

• Test all new functionality, which includes in this case the two modified functions both with and without progress bar. Don't submit a PR without testing it.
• Also update and test lmer_crossvalidation_test()
• Update the docstrings of the modified functions where applicable.

[smathot]

ps. do you think this is the part where it might be helpful to build in the possibility for multiprocessing? That would drastically speed up the permutation tests (which now take many hours).

Potentially yes, but before implementing this, I would first check whether this will actually speed things up. statsmodels already does multiprocessing (but doesn't seem to be using all cores by default).