Representative instance of a cluster - hierarchical clustering

Question

I'm using the Agglomerative hierarchical cluster method to cluster a set of data. Where the dataset I use for clusrting is a trajectories. I use a custom distance function to estimate the distance between the trajectories. The matlab code is as follow: Z = linkage(ID,'single','@my_distfun');

After clustering the data; I would like to find the representative instance ( or trajectory).

How can I find the representative instance (trajectory) of each cluster?

Answer 1

Hierarchical clustering does not have a concept of representative instances.

You will have to decide upon a definition yourself.

For example, you could use the element with the smallest average distance to all others. Or the one with the smallest average squared distance, or ... many other options.

"Representative" is a subjective term.