I do not often get to play with networks, yet I find them fascinating and full of knowledge gathering potential. The data visualization works of Moritz Stefaner, Jer Thorp, and Mark Lombardi captivate me. I am intrigued by relationships, how we perceive them, and how we can understand them.
Gephi, the "Open Graph Viz Platform", is not just for the hobbiest node nerd. It is a hardcore, professional tool for network researchers and other smarty pants. If you know the difference between Yifan Hu and Fruchterman Reingold, then you can use this tool effectively. But you do not need to be rich, as the software is completely free to download and use.
So what is Gephi capable off?
|Cost||Free and open source (they take donations)|
|Ease of Use||Moderate|
|Operating Systems||Windows, Max OSX, Linux|
|Export Formats||Image: SVG, PDF — Graph: CSV, GEXF, GraphML, GDF|
|Maturity (age of software)||unknown|
|Customer Service||None provided; there is community support via the forums.|
|Data Import Formats:|
|other||CSV, GEXF, GDF, GML, GraphML, Pajek NET, GraphViz DOT, UCINET DL, Tulip TPL, XGMML|
— Options! Lots and lots of options. Network layout, fonts, edge size, node size, borders, colors, labels, etc. You name it, it's probably in there.
— Grouping. Ability to group nodes by data points.
— Community-detection. Gephi can identify groups by using its modularity algorithm.
— Reduction. The ability to filter out practically anything in order to make a more coherent graph.
— Statistics! I'm sure this is really cool, but I'm not educated enough to know. If you know your Eigenvector Centrality from your Average Clustering Coefficient, then you will love this feature.
— Export. You can export your graph as SVG or PDF.
— Interface is a bit cluttered. Multiple levels of tabs and redundant buttons make it a bit confusing to navigate. This will probably wane with long term use of the tool.
— A bit buggy. The undo, cut, paste, etc. menu items never seem to work for me. Certain settings remained "on" even after I turned them "off."
— No documentation. There are a couple of user guides that are helpful, but lacking.
Overall, Gephi is a useful and interesting tool. It allows you to explore, create, and analyze network graphs in a fairly easy way. It offers many visualization options for any type of network and supports up to one million nodes and edges.
There are some plugins available for Gephi that extend the functionality. I used one called GeoLayout to make the Minard graph below.
The only thing keeping Gephi from being a professional grade tool is its bugginess and lack of documentation. If its development community can sustain it, Gephi should be able to improve and become a more robust software tool.
For the Purists
Gephi is a purist's delight. All the network graphing functionality is based on cold, hard science. If you recently read the Holten and van Wijk paper, you will like Gephi. It has loads of options but all within the confines of good taste.
For the Aestheticians
While there are no progressive or experimental ways of graphing networks with Gephi, you might still be happy to use it for its ease of exploration. It allows you to customize the look of your graph in many ways. It allows for proportional labels and label truncation, different types of edges based on if its directional or not, and everything from node color to group highlighting. I have to say, I was impressed by the level of visual customization. There are a few things that are overlooked, however, such as overlapping labels, annotation, and so forth. Since the graphs are SVG exportable, at least some of these visual problems can be rectified.
Please let us know your thoughts in the comments below! Thanks!
Kim Rees is a partner at Periscopic, a socially-conscious Information Visualization firm specializing in helping nonprofit organizations and like-minded companies convey important messages and elevate public awareness.