I want to cluster ~22000 points. Many clustering algorithms work better with higher quality initial guesses. What tools exist that can give me a good idea of the rough shape of the data?
I do want to be able to choose my own distance metric, so a program I can feed a list of pairwise distances to would be just fine. I would like to be able to do something like highlight a region or cluster on the display and get a list of which data points are in that area.
Free software preferred, but I do already have SAS and MATLAB.
Best Answer
GGobi (http://www.ggobi.org/), along with the R package rggobi, is perfectly suited to this task.
See the related presentation for examples: http://www.ggobi.org/book/2007-infovis/05-clustering.pdf