Find unique elements for a given column in a table model

I need to find each unique combination in a table
Suppose I have a table that looks like this
Column1 Column2 Column3
A C F
A C F
A D F
B C F
B C G
B D F
B D G
B E F(1) I need to understand that Column1 is composed by two different elements A and B
(2) Then for each element found in column1 I need to filter the table  the result will be two tablesColumn1 Column2 Column3 A C F A C F A D F Column1 Column2 Column3 B C F B C G B D F B D G B E F Then for each table do the same with Column2 Column1 Column2 Column3 A C F A C F Column1 Column2 Column3 A D F ... and so one with each Column on the table
I suppose thar the filtering of the table can easily be done via QSortFilterProxyModel
However I am not sure what to use to perform operation (1) i.e. to understand for a given column how many different elements the cloumn is composed by..... Maybe someone will have a clever idea to solve this.