R: Save multiple igraph plots

I have a function that creates multiple network plots using the igraph package and stores the networks in a list (g.list is the final output).

The function looks like this - and uses a list of dataframes (nodes and edges) to create the networks.

 network.fun <- function(nodes, edges){

  g <- graph_from_data_frame(d = edges, vertices = nodes, directed = FALSE)

  V(g)$color <- ifelse(V(g)$Treatment == "Water", ff.1[3], ff.1[4])

  w1 <- rescale(E(g)$weight, to = c(0,10))

  m1 <- layout_nicely(g) 

  plot(g, vertex.label.color = "black",
                   edge.color = 'dark grey', edge.width = w1, 
                   layout = m1, vertex.size = 24, vertex.label.font=2, 
                   vertex.label.dist=2.3, vertex.label.degree=4.3)


  return(g)


}

g.list <- map(out.list, ~ network.fun(nodes = .x$nodes, edges = .x$edges))

I want to know if it is possible to save each plot as a png file as it is created. I have 108 plots that are created and so would also like the plots to be named according to the nodes/edges dataframe name used to create them.

Solution

It doesn't look like you can save an igraph to an object, but you could save the plot directly by wrapping it in ggsave() like this:

 ggsave(paste0(plotName, ".png),
        plot(g, vertex.label.color = "black",
                       edge.color = 'dark grey', edge.width = w1, 
                       layout = m1, vertex.size = 24, vertex.label.font=2, 
                       vertex.label.dist=2.3, vertex.label.degree=4.3),
        height = 5, width = 5, dpi = 1000)

You can add a plotName argument to your function and define it with a string (e.g. plotName = "plot_1"): if you're mapping over out.list, you can use the names of out.list like this:

map2(out.list, names(out.list), ~ network.fun(plotName = .y, nodes = .x$nodes, edges = .x$edges))