Combining/Removing Edges - igraph

Question

I am creating a circular lattice graph and considering its corresponding full graph. I call the edges in the full graph that are NOT in the lattice graph "non lattice" edges. Now, I want to select a number of edges from the lattice to remove and then I want to add a number of randomly selected edges from the non lattice edges to create a NEW graph. Here is a small example, you will see where it breaks down (last line). Basically, I am having trouble with the edge lists being sequences. Also, if I can do this without have to name all of the nodes that would be better- eventually, I will have large graphs! Here is my current code:
n <- 5 #number of nodes
k <- 1 #number of neighbors for lattice connections
g <- make_lattice(length = n, dim = 1, nei = k, circular = TRUE) #lattice
V(g)$name <- letters[1:n] #name nodes
lat_e <- E(g) #lattice edges
g1 <- g #make a copy
g1[V(g1), V(g1)] <- TRUE #add all possible edges
g1 <- simplify(g1) #remove loops
newe <- E(g1)
non_lat_e <- difference(newe, olde) #non lattice edges
n_switch <- 2 #want to change 2 lattice edges to
non_lattice edges
e_rem <- sample(1:length(lat_e),n_switch)
e_add <- sample(1:length(non_lat_e), n_switch)
g <- delete_edges(g, lat_e[e_rem]) #delete lattice edges
g <- add.edges(g, non_lat_e[e_add]) #add non lattice edges. ERROR

Answer 1

You can't refer to nodes from one graph when adding edges to a new graph. You'll need to provide a pairwise vector by name in order to add new edges. Something like this
non_lattice_edges <- ends(g1, non_lat_e[e_add]) %>%
t() %>%
as.vector()
g <- add.edges(g, non_lattice_edges)
If you never delete a vector, then you don't need add vertex names because the vertex indices will stay consistent. Here is your code, but without the named vertices:
n <- 5 #number of nodes
k <- 1 #number of neighbors for lattice connections
g <- make_lattice(length = n, dim = 1, nei = k, circular = TRUE) #lattice
lat_e <- E(g) #lattice edges
g1 <- g #make a copy
g1[V(g1), V(g1)] <- TRUE #add all possible edges
g1 <- simplify(g1) #remove loops
newe <- E(g1)
non_lat_e <- difference(newe, lat_e) #non lattice edges
n_switch <- 2
e_rem <- sample(1:length(lat_e),n_switch)
e_add <- sample(1:length(non_lat_e), n_switch)
g <- delete_edges(g, lat_e[e_rem]) #delete lattice edges
non_lattice_edges <- ends(g1, non_lat_e[e_add]) %>%
t() %>%
as.vector()
g <- add.edges(g, non_lattice_edges)