Controlling which edges are visible in a network diagram in igraph in r

Question

I have a the following diagram created in igraph

set.seed(1410)
df<-data.frame(
"site.x"=c(rep("a",4),rep("b",4),rep("c",4),rep("d",4)),
"site.y"=c(rep(c("e","f","g","h"),4)),
"bond.strength"=sample(1:100,16, replace=TRUE))

library(igraph)
df<-graph.data.frame(df)
V(df)$names <- c("a","b","c","d","e","f","g","h")
layOUT<-data.frame(x=c(rep(1,4),rep(2,4)),y=c(4:1,4:1))
E(df)[ bond.strength < 101 ]$color <- "red"
E(df)[ bond.strength < 67 ]$color <- "yellow"
E(df)[ bond.strength < 34 ]$color <- "green"
V(df)$color <- "white"
l<-as.matrix(layOUT)
plot(df,layout=l,vertex.size=10,vertex.label=V(df)$names,
edge.arrow.size=0.01,vertex.label.color = "black")

I want to show all the vertices/nodes but only edges where bond.strength > 34 (i.e. only the red and yellow edges). I can control this by setting bond.strength < 34 to white but it is not pretty when done on my actual data set as the white edges "cut through" the other edges i.e.

Are there other way of simply controlling which edges are visible whilst showing all the vertices? Thanks

Answer 1

I wonder what happens if you set the color of the lines to be transparent, something like:

E(df)[ bond.strength < 34 ]$color <- "#FF000000"

I cooked up that color number with:

 hsv(1,1,1,alpha=0)

Alternatively, you could go in and omit them from your edgelist.