How can I show density of 3 values on 1 map?

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06-24-2016 08:12 AM
ELTerrell
New Contributor III

I have a density map of Republicans, Democrats, and Unaffiliated voters addresses in a county.  I've made it into a density map for each one.  However, my director is asking if there's a way to show all 3 party affiliations on one map to compare.  I have no idea how this would work.  Any suggestions?

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5 Replies
DanPatterson_Retired
MVP Emeritus

If it is point density or even kernel density, the problem is that it returns a value per unit area

Understanding density analysis—Help | ArcGIS for Desktop

which means that you can't simply add the rasters together or use the Con statement to display the results without losing some information.  Have you ruled out producing a layout showing the 3 results side-by-side? or tried just showing the points themselves?  A visual of your current state of the data might help in the visualization

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ELTerrell
New Contributor III

Yeah, that was what I did first.  Then he asked for all three on the same map if possible but I was skeptical it would work.

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DarrenWiens2
MVP Honored Contributor

Whether or not this symbology will be coherent on your map, I don't know, but I'd at least consider creating an RGB representation of your data, where R = Republican proportion (out of 255), B = Democrat proportion (out of 255) and G = Unaffiliated proportion (out of 255).

400px-RGBCube_b.svg.png

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ELTerrell
New Contributor III

Any recommendation on where to find information on how to do this?

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DarrenWiens2
MVP Honored Contributor

I explain it here: Is anyway to Analysis without density?

Basically, make one raster for each group, scaled to values from 0-255 (0 = 0% support, 255 = 100% support). Then run Composite Bands tool to combine into one RGB raster.