[R] HELP: how to add weight to a [x,y] coordinate

[Jan Akko Eleveld]

Anyone who can help me with the following question?


How can I add weight to [x,y] coordinates on a graph/scatterplot?


Background:
Monte Carlo simulation generated 730,000 [x,y] coordinates with a weight attached (from 0-0.5).  
Both x and y are rounded and fit on a raster with x-axis 0-170 months (smalles unit = 1 month) and y-axis 0-6 (smallest unit=0.1). 
I would like every [x,y] to add its weight, so that after all 730,000 [x,y] are plotted, a maximum likelyhood becomes apparent through the size of the point that are made up by accumulated weights. 

Thank you in advance for any thoughts!

Best, Akko Eleveld