Create groups based on values from two columns.

Hi, 

I have requirement in which I need to create a new column based on the different combination of values from some other columns.  

For example Column Product contains - A,B,C fields and Column category contains - D,E,F. The new column is created as :

 Combination || New column values         

A & D              - 1

B & E               - 2

C & F              - 3 

Thanks in advance