To combine modules, set non-present cell types to 0

[halterc]

It would be nice, if I see for example a signal in the CD4 and CD8 cells to be able to combine these modules and see how samples cluster in the feature PCA or sample distance PCA based on the combined modules.
If all feature matrices have the same dimensions (i.e. a row for each sample), it would be much easier to do this, e.g. by setting non-present cell types to 0