Common MNE annotation names do not work with nilearn

[rob-luke]

Whats the problem?

Nilearn recently changed the requirements for design matrix column names in nilearn/nilearn#3025 which disallowed strings containing only numbers and strings with / as column names.

Getting rid of the numbers is no problem, I prefer meaningful annotation names anyway.

However, I think its common in MNE to use names like tapping/left or response/right. See https://mne.tools/dev/auto_tutorials/epochs/40_autogenerate_metadata.html?highlight=hed#keeping-only-the-first-events-of-a-group

But nilearn now requires that the column names pass the following test:

'response/right'.isidentifier()
# False

'response_right'.isidentifier()
# True

See lines: https://github.com/nilearn/nilearn/blob/ab9c68e502c4b92695cd658f5839a8207fd5e07e/nilearn/glm/first_level/hemodynamic_models.py#L428-L436

Solution

See #403 for an initial attempt at a fix. Other suggestions are welcome