Igraph package R issue with layout_on_grid

Question

I'm trying to plot a graph with layout_on_grid and receiving the message

Warning message: In if (axes) { : the condition has length > 1 and only the first element will be used

It not only gives the warning, but don't apply the expected layout.

It does not seem to be an issue from the graph itself

library(igraph)

rG <- erdos.renyi.game(25,0.2)
plot(rG)

as we can see

but with the layout, the warning.

plot(rG, layout_on_grid(rG, dim=2))

I have tested with directed and undirected edges and with edges with null or positive weights.

and the layout works here

el <- matrix(nc=3, byrow=TRUE,
             c(1,2,0, 1,3,2, 1,4,1, 2,3,0, 2,5,5, 2,6,2, 5,2,1, 3,4,1,
               3,7,1, 4,3,0, 4,7,2, 5,6,2, 5,8,8, 6,3,2, 6,7,1, 6,9,1,
               6,4,3, 8,6,1, 8,9,1, 7,10,4) )
g <- add_edges(make_empty_graph(10), t(el[,1:2]), weight=el[,3])
plot(g)

plot(g, layout=layout_on_grid(g, width = 4))

Any ideas I could be doing wrong here?

Answer 1

The 2nd argument of plot.igraph is axes . You were effectively giving it a matrix, where it wants a logical TRUE/FALSE value. So it used the first value of the matrix, coerced it to a boolean value and threw out a warning.

After adding the layout argument it will work as expected:

plot(rG, layout=layout_on_grid(rG, dim=2))