How to group a XDF file and concatenate the strings in the columns?

Question

I am new to revoScaleR and would like to know who I can group a XDF file and concatenate the values of a column in a group. For example if I have data like

A B
1 one
1 two
2 three
2 four

I would like the following output

A B
1 one,two
2 three,four