To visualize my flights for each year, I’ve created a series of multigraphs. Each vertex (circle) is an airport, and the bigger the circle, the more often I’ve visited the airport that year. Each edge (arrow) is a flight, color-coded by airline. This shows at a glance which routes I fly the most often (they have the most arrows), and which airlines I fly on which routes.
I create my flight graphs as GraphML XML documents, and use yEd Graph Editor to layout the graphs and export them as SVG images.
To create the GraphML documents, I wrote a GraphML module within my Flight Historian, a Ruby on Rails application. I pass a collection of flights from the Flight Historian database (filtered by a given year) to a
graph_flights method. The method then generates the appropriate XML for a yEd-flavored GraphML file, with airport vertexes/nodes sized by frequency and flight edges color-coded by airline.