Cluster Analysis on musical data from Last.Fm

For each user the list of 50 most played composers (and respective playcounts) was fetched. This list represents musical preference. A user can be seen as a point in a multi dimensional space where the composers are the dimensions and the 50 playcounts of a user its coordinates.
Using principle component analysis, the large composer space (4932 artists) can be reduced to 64 dimensions, retaining 99% of the variance in the data.
As measure of similarity between two users we use the correlation of their vectors in the reduced composer space. The graph on the left shows again the 388 users, each node connected to its three most similar neighbours
The layout of the graph is realised by a force directed algorithm. The colors represent 8 clusters in the 64 dimensional space that are found by the so called QT-clustering algorithm (quality treshold clustering). It is interesting to note that these clusters also happen to be perfectly separated by the force directed layout of the (synthetic) graph. Below is a list of the 10 most important dimensions (composers) of the 8 cluster centres. Combining cluster C-38 with C-24 and C-11 ons arrives at the same clustering as the previous ( graph. This shows that our similarity measure is able to make a much finer distinction in taste than the undisclosed method of

C-60 C-55 C-54 C-49 C-48 C-38 C-24 C-11
17.3Fabrizio De André 20.7Sufjan Stevens 7.6Johann Sebastian Bach 8.3Placebo 6.8Esbjörn Svensson Trio 23.8The Beatles 24.9Jamiroquai 10.9Aziza Mustafa Zadeh
2.9Pink Floyd 2.5Regina Spektor 4.5Wolfgang Amadeus Mozart 8.0Muse 3.5Keith Jarrett 5.0Queen 1.5Sting 2.2Anouar Brahem
1.6Radiohead 2.2The Beatles 4.4Ludwig van Beethoven 3.8Mew 2.3Bill Evans 3.6Jamiroquai 1.5Queen 1.6Johann Sebastian Bach
1.6Franco Battiato 1.8Rufus Wainwright 4.3Frédéric Chopin 2.7Radiohead 2.0Miles Davis 1.3Pink Floyd 1.5The Beatles 1.1Tori Amos
1.5Francesco Guccini 1.3Death Cab for Cutie 3.3Franz Schubert 2.5Lapko 2.0Chick Corea 1.2Led Zeppelin 1.2Red Hot Chili Peppers 1.1Kings of Convenience
1.2The Beatles 1.1The Shins 2.8Johannes Brahms 2.3Scandinavian Music Group 1.7Pat Metheny 1.0Depeche Mode 1.1Michael Jackson 1.0Esbjörn Svensson Trio
1.2Vinicio Capossela 1.1Elliott Smith 2.1Pyotr Ilyich Tchaikovsky 2.1Zen Café 1.7Herbie Hancock 0.9Muse 1.1Dream Theater 1.0Radiohead
1.1Modena City Ramblers 1.0Belle and Sebastian 2.1Georg Friedrich Händel 2.0The Killers 1.7Brad Mehldau 0.8Radiohead 1.0Arctic Monkeys 0.9Dream Theater
1.1Rino Gaetano 1.0Iron & Wine 1.9Antonio Vivaldi 1.9Coldplay 1.5Thelonious Monk 0.7The Who 0.9Jaco Pastorius 0.9The Real Group
1.0Elio e le Storie Tese 1.0Jack Johnson 1.9Felix Mendelssohn 1.8The Ark 1.3John Coltrane 0.7Red Hot Chili Peppers 0.8Litfiba 0.9Wolfgang Amadeus Mozart