Group preprocessed BOLD files by unique sets of entities, ignoring run and direction.
We only ignore direction for the sake of HCP.
This may lead to small problems for non-HCP datasets that differentiate scans based on
both run and direction.
Parameters:
in_files (list of str) – A list of preprocessed BOLD files to group.
Returns:
out_files – The grouped BOLD files. Each sublist corresponds to a single set of runs.