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How to Smart Map: Predominance

Compare attributes in your data using smart mapping

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This quick guide introduces how to map multiple attributes within a single map using the technique known as predominance. 

What is a Predominance Map?

An election map is an example of a predominance map. It simply tells you which of two or more candidates have the highest total vote count. 

For example, this map shows the predominant count of votes for President in North Dakota voting precincts from the 2008 election.

Areas with more Republican votes are in red 

Areas with more Democrat votes are in blue

White represents an exact tie

Darker colors indicate a higher predominant vote for that party. Lighter colors indicate that party barely won the precinct. These measures represent the strength of the predominance over the other attributes.

When to use Predominance

Smart mapping lets anyone quickly discover patterns from attributes in their data and make meaningful maps from them. You can use smart mapping to analyze multiple columns of related data, in order to determine which has the highest, or predominant, value for each feature. Try a predominance map anytime you see multiple columns of data that share a common subject and unit of measurement. 

For example, I have data regarding the crop output of US counties. Within my table, there are five attributes which track the amount of harvested acres by the type of crop:

I can use predominance to determine which crop type produced the most yield. It compares the values of my five attributes and immediately tells me which one is the largest value. The level of transparency tells me HOW predominant the attribute is compared to the other attributes. You can see this in the legend as the "Strength of predominance".


Predominance can also provide a sum of the five attributes in order to provide context about how many total acres were harvested from these five crops. This is represented by the size of the symbol, and can be seen in the map's legend as "Sum of categories".


How it's Done

To make a predominance map within the ArcGIS Online and ArcGIS Enterprise Map Viewer, simply select up to ten attributes within the smart mapping interface. To do this, go to Change Style and choose to "add attribute". Smart mapping will provide the "Predominant Category" and "Predominant Category & Size" options.

Let's quickly walk through an example together:

Further Customization

If you want to compare more than ten attributes, you can do so using an Arcade Expression to calculate the predominant value. 

Arcade is a simple expression language that allows you to create custom cartography, attributes, labeling, and more. The following blogs introduce Arcade and how to use it to create a predominance map similar to what is created by smart mapping:

Use Arcade Expressions to Map Your Ideas

Creating a Predominance Visualization with Arcade

Using a set of Arcade Expressions, you can map the predominance of more than 5 attributes

Check out this map for an example of the settings used when created a custom predominance map. You'll notice that the pop-up also includes the predominant category. Use an Arcade Expression to create a clear pop-up describing the predominant value, which helps your audience better understand the map. Including a chart in the pop-up also helps tell a clear story.

Get Started Today

Use predominance to compare multiple attributes within your datasets, and quickly get a map which shows the largest value. This technique is easy to use and can help you visualize new patterns within your datasets. 

Learn more about smart mapping and how to use the predominance mapping styles at the ArcGIS Online Help pages:

Change Style: Numbers

Predominant Category

Predominant Category and Size

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