[R] finding clusters in a network

[jv37 at columbia.edu]

Hello,

I have data with 1500+ observations. Each observation has two
attributes _id_, a self identifier, and _parentid_, identifying a
single association with a previous observation. The value of
_parentid_ can either be the _id_ value of that single associated
observation or NA. Different observations can be associated with
the same previous observation and share the same value for
_parentid_. In this way, these 1500+ observations form a directed
graph made up of several disconnected clusters (of various sizes)
and several isolates. I need to identify these disconnected
clusters of two or more observations. I have been trying to figure
out how to use the network, sna, and kinship packages, but, without
little time before finals to read the relevant literature, I am
desperate for some helpful advice.

Thank you in advance--

John