Nested for-loop skips loops - r

Question

this is my problem:
I have a grid (see plot below), and I need to get and store in a list the coordinates of each vertex of each block (cell). The order of blocks that I need is '1-1', ... '4-1', '1-2', ... '4-2'. To keep it simple I'm just working with the indexes for now.
Based on two vectors with the common East and North coordinates I've written a little function, which is partially producing the output that I need. It is skipping the cell '1-2' and '2-2' (see output below). I can't see where exactly is the error, but I suspect that the issue is in my nested for loop. (There are many questions on for loop, but none helped me with my problem).
Any help will be appreciated and apologise if this is too basic to be asked here.
vectors:
x.breaks <- c(191789.1, 291789.1, 391789.1)
y.breaks <- c(5172287, 5272287, 5372287, 5472287, 5572287)
Function:
getting_vertices <- function(x.breaks, y.breaks){
xs <- list()
ys <- list()
polys <- list()
for(i in 1 : (length(x.breaks)-1)){
xs[[i]] <- c(i, i+1 , i+1, i, i)
}
for(j in 1 : (length(y.breaks)-1)){
ys[[j]] <- c(j, j, j+1, j+1, j)
}
for(v in 1 : length(sapply(ys, length)) ){
for(k in 1: length(sapply(xs, length))){
polys[[v*k]] <- cbind(xs[[k]], ys[[v]])
}
}
return(polys)
}
getting_vertices(x.breaks, y.breaks)
Output (this is partially correct):
[[1]]
[,1] [,2]
[1,] 1 1
[2,] 2 1
[3,] 2 2
[4,] 1 2
[5,] 1 1
[[2]]
[,1] [,2]
[1,] 1 2
[2,] 2 2
[3,] 2 3
[4,] 1 3
[5,] 1 2
[[3]]
[,1] [,2]
[1,] 1 3
[2,] 2 3
[3,] 2 4
[4,] 1 4
[5,] 1 3
[[4]]
[,1] [,2]
[1,] 1 4
[2,] 2 4
[3,] 2 5
[4,] 1 5
[5,] 1 4
[[5]]
NULL
[[6]]
[,1] [,2]
[1,] 2 3
[2,] 3 3
[3,] 3 4
[4,] 2 4
[5,] 2 3
[[7]]
NULL
[[8]]
[,1] [,2]
[1,] 2 4
[2,] 3 4
[3,] 3 5
[4,] 2 5
[5,] 2 4

Answer 1

The logic behind the line polys[[v*k]] <- ... is incorrect, for example, v=2, k=1 will overwrite v=1, k=2. There are no combinations of v and k that make 5 or 7, hence these entries are empty.
I expect that you meant to write something like:
polys[[v+(k-1)*(length(ys))]] <- ...
or
polys[[k+(v-1)*(length(xs))]] <- ...
depending on the order that you want your results in