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Achieve min/max Values for Symbology from another Layer?

November 16 2011 | 0 comments
Categories: Cartographic Concepts, Cartographic Design, Symbology

I've got 3 maps with different percentages of population growth and shrinkage. The final map is 2050 with the final shrinkage of 80% of the 2010 population (dark blue). In the 2025 map the maximum shrinkage is only 35% but also also dark blue. But in comparison to 2050 it only the half. How do I apply the min/max Values of 2050 to a map with values of 2025? This way both legends would be coherent.

Mapping Center Answer:

It sounds like you want to show all three maps using the same classification and symbology definition so you can visually compare them with one another.

To do this, classify and symbolize the layer with the greatest variance and which extends beyond the min and max values in your other layers (this sounds like your 2050 layer). Open Layer Properties > Symbology for one of your other layers and choose Import. In the Import dialog box, select "Import symbology definition from another layer in the map or from a layer file". Choose your symbolized layer and then choose to import the "Complete symbology definition". Your second layer will be classified and symbolized the same as the first.

Be mindful that taking this approach might lead to many of your areas on the layer with less variation being classified in the same class so it's important to choose your classes on the first layer carefully to ensure they make sense when used for other layers.

Generally though, this is a good way to make multiple choropleth maps that you can compare.

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