Much of the analysis of a network is actually just measuring its various parts and pieces. How many nodes does it have? How are those nodes connected to each other? How many links does it have and how many ways can we traverse those edges? In this section, we will learn many of the common ways to measure a network.
One way to describe a network is through its degree distribution. The degree of a node is the number of its connected edges. In an undirected graph, the degree of a node is the count of all the edges coming out of it. The degree distribution tells us how many nodes had a degree of 0, how many had a degree of 1, then 2, and so on. Figure 4 shows a histogram of the degree distribution for a simple undirected graph. Two of the nodes have a degree of three, two of the nodes have a degree of two, and one node has a degree of one:
Figure 4. Simple undirected graph and its degree distribution
Figure 5 shows some alternative shapes for degree distributions...
