Playing with DAG communities by adding 1 edge at different places to a base DAG

playing_w_DAG_communites.R

library(igraph)
library(grid)
library(gridGraphics)

#### Make a base graph ####
g <- make_tree(15) +
  edges(4, 7,
        8, 14,
        9, 10, 
        15, 13)

#### Confirm that it is a DAG ####
is_dag(g)

#### Bin each node into a community by using Walktrap ####
wc <- cluster_walktrap(g)

#### Layout of nodes to have a consistent layout for all variations of graph ####
l <- matrix(
  c(1, 5,
    2, 3,
    2, 7,
    3, 4.5,
    4, 1,
    4, 10,
    3, 6.5,
    5, 4.5,
    4, 3,
    5, 3,
    5, 1,
    5, 10,
    5, 8, 
    5, 6.5,
    4, 8),
  ncol = 2,
  byrow = T
)


#### Plotting defaults stored in nodes and edges ####
E(g)$label = ''
V(g)$label.font = 2
V(g)$label.cex = 1.5
V(g)$label.color = 'whitesmoke'

#### Plot and store graph into a grid object ####
plot(wc, g, layout = l, main = 'Starting DAG')
grid.echo()
a <- grid.grab()

#### Add an edge to the base graph ####
#### Create a grid object for the plot ####
#### Create a grid object for title (for some reason the "main" attribute of plot disappears ####
addEdgeToDAG <- function(g, e, l) {
  new_g <- g + edge(e)
  V(new_g)$label = ''
  V(new_g)$size = 0
  E(new_g)$label = ''
  
  wc <- cluster_walktrap(new_g)
  plot(wc, new_g, layout = l, main= paste0(e[1], ' -> ', e[2]))
}

grabbedPlots <- lapply(list(c(4, 5), c(3, 15), c(14, 13)), function(x){
  addEdgeToDAG(g, x, l)
  grid.echo()
  temp <- grid.grab()
  list(plot = temp, text = textGrob(paste0(x[1], ' -> ', x[2]),  x = .5, y = .85))
})



png('walktrap_play.png', width = 600, height = 450)

grid.newpage()

pushViewport(viewport(x = .33, y = .5, width=.66, height= 1))
grid.draw(a)
grid.draw(textGrob("Exploring Changes to DAG Walktrap Community\nBy Adding Only 1 New Edge",x = .5, y = .1))

popViewport()
pushViewport(viewport(x = 1 - .2, y = 1 - .15, width=.32, height=.32))
grid.draw(grabbedPlots[[3]]$plot)
grid.draw(grabbedPlots[[3]]$text)

popViewport()
pushViewport(viewport(x = 1 - .2, y = .5, width=.32, height=.32))
grid.draw(grabbedPlots[[1]]$plot)
grid.draw(grabbedPlots[[1]]$text)

popViewport()
pushViewport(viewport(x = 1 - .2, y = .15, width=.32, height=.32))
grid.draw(grabbedPlots[[2]]$plot)
grid.draw(grabbedPlots[[2]]$text)

dev.off()