Direct Vector routing

Hi all !

I just learning Direct vector routing. I confused about the part where a router whether considers the upddated or initial Direct vector from it's neighbors. For example, R1's neighbors are R2 and R3.

R1: [R1,R2,R3,R4] or R1= [0,2,4,inf]

R2: [R1,R2,R3,R4] or R1= [2,0,1,4]

R3: [R1,R2,R3,R4] or R1= [4,1,0,2]

R4: [R1,R2,R3,R4] or R1= [inf,4,2,0]

N.B: other all router are neighbors of R2; all other routers are neighbors of R3; Only R2, R3 are neighbors of R4

After round 1 update, R1 = [0,2,3 (R2),5(R2)]

So if I want to update R2, somehow it says R1 and R2 are in parallel so we are assuming that R2 did not get the updated info from R1.

But when it came to R4 ,which is on the other side of R1 and not a neighbor, it used the R1's updated table not the initial one.

Why is that? When do I consider other routers' updated table and the initial table?