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Node degree

As explained in Graph Algorithms for Data Science

Node degree is the number of graph relationships incident to a node, with directed graphs potentially distinguishing incoming and outgoing relationships.

Node degree counts the links incident to a node. Measuring degree across a network helps reveal whether connections are distributed evenly or concentrated in a small number of highly connected nodes. section 5.0

For directed networks, separate the connections by direction:

  • In-degree counts incoming connections. section 5.6
  • Out-degree counts outgoing links. section 5.6
  • The overall degree distribution describes how many links nodes typically have. Random-network models are associated with a Gaussian distribution, whereas real-world networks commonly follow a power-law distribution with many low-degree nodes and a few highly connected ones. section 5.0 section 5.6

Web pages and URL links

Treat web pages as nodes and URL links as directed relationships. A page’s in-degree counts pages linking to it, while its out-degree counts the links it publishes. Comparing these values helps distinguish rarely connected pages from unusually connected ones. section 5.0

Figure 5.1 Random network degree distribution
05-01

Use the random-network distribution figure to compare the expected concentration of node links. section 5.0

Figure 5.2 Scale-free network degree distribution
05-02

Use the scale-free distribution figure to see how real-world networks can contain many low-degree nodes and a small number of hubs. section 5.0

How Graph Algorithms for Data Science covers it

How deep it goes
Defines degree and distinguishes directed in-degree from out-degree, but does not develop a calculation procedure or implementation.
Examples
Uses handshakes, web pages, and URL links to illustrate links, directed degree, and contrasting degree distributions.
What you can do after
Evaluate network structure by identifying typical connectivity, low-degree nodes, and highly connected nodes.
How it connects
Connects node degree with random networks, Gaussian distributions, power-law distributions, directed networks, and PageRank.

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This explainer was generated by Manning's knowledge graph from the text of Graph Algorithms for Data Science. The section links point to the parts of the book it draws on.