basic ggplot2 network graphs

March 17, 2011
By

(This article was first published on Recology, and kindly contributed to R-bloggers)

I have been looking around on the web and have not found anything yet related to using ggplot2 for making graphs/networks. I put together a few functions to make very simple graphs. The bipartite function especially is not ideal, as of course we only want to allow connections between unlike nodes, not all nodes. These functions do not, obviously, take full advantage of the power of ggplot2, but it’s a start.


# ggplot network graphics functions
# g = an igraph graph object, any igraph graph object
# vplace = type of vertex placement assignment, one of rnorm, runif, etc.
 
gggraph <- function(g, vplace = rnorm) {
 
require(ggplot2)
 
g_ <- get.edgelist(g)
g_df <- as.data.frame(g_)
g_df$id <- 1:length(g_df[,1])
g_df <- melt(g_df, id=3)
xy_s <- data.frame(value = unique(g_df$value),
x = vplace(length(unique(g_df$value))),
y = vplace(length(unique(g_df$value))))
g_df2 <- merge(g_df, xy_s, by = "value")
 
p <- ggplot(g_df2, aes(x, y)) +
geom_point() +
geom_line(size = 0.3, aes(group = id, linetype = id)) +
geom_text(size = 3, hjust = 1.5, aes(label = value)) +
theme_bw() +
opts(panel.grid.major=theme_blank(),
panel.grid.minor=theme_blank(),
axis.text.x=theme_blank(),
axis.text.y=theme_blank(),
axis.title.x=theme_blank(),
axis.title.y=theme_blank(),
axis.ticks=theme_blank(),
panel.border=theme_blank(),
legend.position="none")
 
p
 
}
 
ggbigraph <- function(g) {
 
require(ggplot2)
 
g_ <- get.edgelist(g)
g_df <- as.data.frame(g_)
g_df$id <- 1:length(g_df[,1])
g_df <- melt(g_df, id=3)
xy_s <- data.frame(value = unique(g_df$value),
x = c(rep(2, length(unique(g_df$value))/2), rep(4, length(unique(g_df$value))/2)),
y = rep(seq(1, length(unique(g_df$value))/2, 1), 2))
g_df2 <- merge(g_df, xy_s, by = "value")
 
p <- ggplot(g_df2, aes(x, y)) +
geom_point() +
geom_line(size = 0.3, aes(group = id, linetype = id)) +
geom_text(size = 3, hjust = 1.5, aes(label = value)) +
theme_bw() +
opts(panel.grid.major=theme_blank(),
panel.grid.minor=theme_blank(),
axis.text.x=theme_blank(),
axis.text.y=theme_blank(),
axis.title.x=theme_blank(),
axis.title.y=theme_blank(),
axis.ticks=theme_blank(),
panel.border=theme_blank(),
legend.position="none")
 
p
 
}
 
Created by Pretty R at inside-R.org



g <- erdos.renyi.game(20, 5, type="gnm")
gggraph(g, rnorm)

 
g <- barabasi.game(20)
gggraph(g, rnorm)


g <- grg.game(20, 0.45, torus=FALSE)
gggraph(g, rnorm)

 
g <- growing.random.game(20, citation=FALSE)
gggraph(g, rnorm)

 
g <- watts.strogatz.game(1, 20, 5, 0.05)
gggraph(g, rnorm)



# A bipartite graphs

g <- grg.game(20, 0.45, torus=FALSE)
ggbigraph(g)

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