Use this if you are using igraph from R
| set_edge_attr {igraph} | R Documentation | 
Set edge attributes
set_edge_attr(graph, name, index = E(graph), value)
graph | 
 The graph  | 
name | 
 The name of the attribute to set.  | 
index | 
 An optional edge sequence to set the attributes of a subset of edges.  | 
value | 
 The new value of the attribute for all (or   | 
The graph, with the edge attribute added or set.
Other graph attributes: 
delete_edge_attr(),
delete_graph_attr(),
delete_vertex_attr(),
edge_attr<-(),
edge_attr_names(),
edge_attr(),
graph_attr<-(),
graph_attr_names(),
graph_attr(),
igraph-dollar,
igraph-vs-attributes,
set_graph_attr(),
set_vertex_attr(),
vertex_attr<-(),
vertex_attr_names(),
vertex_attr()
g <- make_ring(10) %>%
  set_edge_attr("label", value = LETTERS[1:10])
g
plot(g)