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Proportional half-disks

March 17 2009 | 0 comments
Categories: Symbology

Are there half-disks within the symbols sets that I can use as graduated symbols?

I am try to create a map showing exports and imports with half-disks facing each other and proportional to the amount of trade for several countries.

Thanks

Mapping Center Answer:

This is a tricky one. While we do indeed have half-disks, they cannot be easily used they way you want to use them. You will run into an offset problem because the anchor point of the symbol is the center of the symbol. So the only way to do this is to create a new layer for every combination of each of the classes of the two variables. A daunting task and one that is most likely not worth the effort.

An alternative is to think about using something other than size for the visual variable. You could, for example, use value (that is, lightness-darkness). If you do, keep the number of classes to a bare minimum -- maybe no more than 3 for each variable. You can also use the symbol set that is downloadable from ArcScripts called "DDV's Population PLUS Marker Symbol Styleset". Here is the link to the download: ttp://arcscripts.esri.com/details.asp?dbid=12011. It contains the half-disk type symbols you are asking about. This is the link to a discussion thread that includes a couple of comments by the author of the symbol set: http://forums.esri.com/Thread.asp?c=93&f=982&t=124551. Finally, here is the link to an article that describes the use of the symbols from this symbol set: http://www.esri.com/news/arcuser/0703/files/mossman.pdf.

You should also check out the European Energy map on the Maps page of Mapping Center -- this is a different take on things.

Good luck!

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