This is our (Jan Krutisch and Wolfgang Wopperer of mindmatters) contribution to the music hack day amsterdam 2009.
The visualisation follows the Streamgraph pattern as described by Lee Byron and Martin Wattenberg
If you are interested, this currently uses the “wiggle” correction, as we have some problems with the “weighted wiggle” algo if the dataset is as sparse as ours.
The graph is rendered using a self written g.raphael plugin which is not quite finished yet.
You’ll need an echonest api key and either set an environment variable ECHONEST_API_KEY or create config/api_keys.yml which contains an echonest: entry.
Calling rake cron once a day is a good idea to populate the database.