Put in a array some element of a structure

Hello, I have a structure with 6 fields like this :

a b c d e f
'1' 3 4 8 9 6
'4' 5 6 2 1 3 
'7' 5 2 1 6 8
'6' 2 1 5 8 4

I called data this structure. For instance if I write data.a I get :

ans = 
'1'
ans =
'4'
ans = 
'7'
ans =
'6'

In my case I just would like to create an array to put data.a inside I mean like this for instance if I call F the array :

F(1) = 1
F(2) = 4
F(3) = 7
F(4) = 6

How can I do this ?

Thank you a lot !