This chapter describes how to produce node-and-edge graphs with R. Node-and-edge graphs are a special case because producing a graph visualization usually requires special algorithms to determine a useful arrangement of the nodes on a page. Several packages are described that provide this facility, notably Rgraphviz and igraph. This chapter also describes how to draw more regular node-and-edge diagrams in R.
The main graphics systems in R, traditional, lattice, and ggplot2, are all focused on producing graphs in the sense of statistical plots. Another common meaning of the term “graph” is a set of nodes with edges connecting them. This chapter describes packages that are focused on producing images ...