Implementing and optimizing a simple graph metric

[Joseph Rushton Wakeling]

Hello all,

I thought I'd do a writeup of the process of implementing and 
optimizing one of the graph metrics in Dgraph, starting from a 
fairly straight copy of pseudo-code in a research paper all 
through the various incremental tweaks that improve performance.
http://braingam.es/2013/09/betweenness-centrality-in-dgraph/

I guess the optimizations made in this process are trivial for 
anyone experienced in D, but I hope the detailed description of 
what changes produce useful speedups might be useful for people 
new to the language.

{Enj,Destr}oy :-)

Best wishes,

     -- Joe