I found a C library for clustering and I was reading about the distance matrix here: it says:
The first step in clustering problems is usually to calculate the distance matrix. This matrix contains all the distances between the items that are being clustered.
If I have a cloud of data (I'm studying web traffic and I'm trying to classify it not with known ports or payload inspection, but with some kind of pattern recognition of collected data such as total number of packets, mean packet size, mean payload size excluding headers, number of bytes transfered), how should the distance matrix be set?
The quote says
This matrix contains all the distances between the items that are being clustered
so some kind of clustering has already been done? I think I'm missing something...