Hi Carlosan,
Thank you very much for your response, but it seems as if what I need is not possible.
I have done this process manually with 6 edges but it is just time-consuming.
I illustrate what I am looking for :-
1) Select one edge in a 12-sided cylinder that has alternate faces extruded
2) Move all edges radially (simultaneously) in the direction as indicated by the arrows - set radial symmetry to 6, select one edge, move it and the rest follow.