Plot of the degree distribution of a graph in R

Question

I have a graph and I want to plot the degree distribution. Example:

> library(igraph)
> g <- make_ring(10)
> degree(g)
 [1] 2 2 2 2 2 2 2 2 2 2
> g2 <- sample_gnp(1000, 10/1000)
> degree_distribution(g2)
 [1] 0.000 0.000 0.001 0.008 0.017 0.045 0.061 0.096 0.103 0.133 0.127 0.102 0.103 0.069 0.046 0.039 0.026 0.012 0.007
[20] 0.000 0.003 0.002

I want to plot the distribution of degrees with log scale, more or less like in the image below:

Answer 1

You can request the log scale directly in the Plot command:

g2   <- sample_gnp(1000, 10/1000)
dg2  <- degree_distribution(g2)
x  <- 1:max(degree(g2)) - 1
zeros <- (dg2 == 0) # para remover os zeros (pois log(0) é infinito)
plot(x[!zeros], dg2[!zeros], log = "xy", 
     xlab = "Log Degree", 
     ylab = "Log Frequency")

The graph of your example will not match your drawing because you simulated the Erdos-Renyi model. Your drawing follows a power law.

For a simulation more like what you want:

g2   <- sample_fitness_pl(10000, 30000, 2.2, 2.3)
dg2  <- degree_distribution(g2)
x  <- 1:max(degree(g2)) - 1
zeros <- dg2 == 0
plot(x[!zeros], dg2[!zeros], log = "xy", 
     xlab = "Log Degree", 
     ylab = "Log Frequency")