Set all types to False in pick_types

Would it make sense to set all arguments in pick_types to False by default? In other words, currently everything is False except for meg. I know where this is coming from, but for people working with EEG, NIRS, or other non-MEG signals, we always have to include meg=False in addition to e.g. eeg=True.

[hoechenberger]

Updated table based on @cbrnr’s and @agramfort’s comments – hope I copied everything correctly.

Type	pick_types() call	master behavior	proposed new behavior
EEG & MEG	pick_types(meg=False, eeg=True)	EEG only	EEG only
EEG & MEG	pick_types()	MEG only	error
EEG & MEG	pick_types(eeg=True)	EEG & MEG	EEG only
EEG	pick_types()	Error?	error
EEG	pick_types(eeg=True)	EEG & MEG	EEG only
MEG	pick_types()	MEG only	error
MEG	pick_types(meg=True)	MEG only	MEG only

[cbrnr]

The next release (0.21) should behave identically to 0.20, but a DeprecationWarning should be raised (something like “The defaults of pick_types will change in the next release. All signal types will be set to False by default (currently, meg=True by default).”).

Release 0.22 should implement the new behavior. Your examples will be:

If you have EEG/MEG:

raw.pick_types(meg=False, eeg=True)  # EEG only, will work as before
raw.pick_types()  # error (no signals picked)
raw.pick_types(eeg=True)  # new option to pick EEG only

If you have EEG:

raw.pick_types()  # error (no signals picked)
raw.pick_types(eeg=True)  # need to select EEG

If you have MEG:

raw.pick_types()  # error (no signals picked)
raw.pick_types(meg=True)  # need to select MEG