What determines the distance between two vertices?

Dec 4, 2010 at 3:11 PM

Hi All,

Once i enter the data and refresh the graph, what determines the distance between two vertices?

I have noticed that when i enter clustered data, a certain vertex from one cluster might show up closer to the other cluster? I mean a vertex might have a different location from the other even if they have the same "Between Centrality" and "Closeness Centrality"?

What determines the distance between two vertices, and also their location? Any help would be greatly appreciated.

Many thanks.

Best,
Walrasian

Dec 5, 2010 at 5:28 PM

Walrasian:

The vertex locations are determined by the layout algorithm you select at the top of the graph pane.  The default algorithm, Fruchterman-Reingold, treats the vertices as if they are bodies that exert physical forces on each other.  It starts by randomly scattering the vertices, then computes the forces and moves the vertices accordingly.  It does this repeatedly, the idea being that the vertices eventually end up in a kind of equilibrium.

The Harel-Koren algorithm works in a similar fashion, although it uses a "multiscale" technique that makes it more efficient when used on large graphs.

Neither algorithm pays any attention to any clusters you have created, which explains why a vertex in one cluster might show up closer to another cluster.  We would like to add another layout algorithm that does reflect clustering, but we haven't gotten to that yet.

-- Tony