In this section, let us see some more structural properties of a graph. Till now we created some simple graphs. It will be better to have some larger graphs to study the structural properties.

The R code for a lot of different networks built from a diverse source of input is available at https://github.com/igraph/igraph/tree/master/nexus/download.

Let's use the US airport network from the repository to show some structural properties of a graph:

url <- "http://sites.google.com/site/cxnets/US_largest500_airportnetwork.txt"
tmp <- tempdir()
dest <- paste(sep="", tmp, "/", "usairport.txt")
download.file(url, dest)

usairport <- read_graph(dest, format="ncol")

We first download the file from an internet URL and use read_graph function to successfully create a graph. Let us now start looking at some structural properties.