Concentration map

[CJ]

Hi all,

I have a dataset with x and y variables. I want to plat these variables on an x-y plot and overlay a heat map that shows the concentration of the points at a given area on the chart. So, the more (x-y-)points there are closely around a point, the darker/redder the colour. of the heat map.

Does anyone have any ideas of how to represent that?

Many thanks,

Chris

[GraphGuy]

There are ways to color the areas behind the plot markers in a gplot (using annotate). And you could do some calculations on the data to do summary counts of the number of obsns/markers in each area, and color the areas accordingly.

I don't have an example that does that 'exact' thing, but here's one that is close:

http://robslink.com/SAS/democd22/heatmap.htm

http://robslink.com/SAS/democd22/heatmap_info.htm