RenderUniqueValues

Unique value renderer

Render features in a layer using a distinct symbol for each unique attribute value.

Use case

A unique value renderer allows you to symbolize features in a layer based on one or more matching attributes. This is typically done by using unique colors, fill styles, or images to represent features with equal values in a string field. A unique value renderer could be used to show different types of trees on a vegetation map by using a symbols corresponding to matching name attributes.

How to use the sample

The map with the symbolized feature layer will be shown automatically when the sample loads.

How it works

Using the UniqueValueRenderer, separate symbols can be used to display features that have a specific value for a given field. In this case, the field is subregions of the USA. While multiple fields can be used, this sample only uses one.

1. A SimpleFillSymbol is defined for each type of feature.
2. SimpleFillSymbol can be applied to polygon features, which is the type of feature contained by this ServiceFeatureTable.
3. Separate UniqueValue objects are created which define the values in the renderer field and the symbol used to render matching features.
4. A default symbol is created to render all features that do not match any of the UniqueValue objects defined.

Relevant API

• FeatureLayer
• ServiceFeatureTable
• SimpleFillSymbol
• SimpleLineSymbol
• UniqueValue
• UniqueValueRenderer

About the data

The map shows U.S. states symbolized by subregion. Symbols are defined for Pacific, Mountain, and West South Central states. All other features are symbolized with the default symbol.

Tags

draw, renderer, symbol, symbology, values