G = findgroups (tt) returns a column of group numbers, one per row of tt, numbering the distinct combinations of its variables in sorted order. A row holding a missing value in any variable belongs to no group and is numbered NaN.

The row times take no part: a timetable groups by its variables, as a table does.

[G, TID] = findgroups (tt) also returns a table with one row per group, holding the combination of values that defines it. It is a table and not a timetable, its rows being groups rather than instants.

See also: splitapply, timetable

Source Code: timetable