spatialpoints: each dot represents 100 individuals?

Hi,

I have a dataset with couple of million of points (individuals) and
would like to do some mapping (I have the coordinates of each point)
but given the number of observation I think it may be usuful to plot
dots which represent 100 individuals (of a given group). Does anyone
know a good way to aggregate up spatialpoints? Any suggestions would
be much appreciated!

Best wishes,
Juta