How to properly define feature_groups for cca_zoo.linear.GRCCA if one of the views does not have any groups?

[JohannesWiesner]

I would like to pass feature_groups over to GRCCA.fit(feature_groups). The left view has some expected groups but the right view does not. It is not clear to me from the documentation how a user should define views for which no feature groups are expected. Should you assign the same number to all features in this case?

Let's say X1 has 4 features and X2 also has 4 features. For X1, the two first features can be assigned to one group and the last two also to one group:

It seems it is not possible to do:

GRCCA.fit(feature_groups=[[0,0,1,1],None]])

Should I do:

GRCCA.fit(feature_groups=[[0,0,1,1],[0,0,0,0]])

in that case?