Attribute-driven symbology

Reflect feature attribution in symbols

You can customize symbols to reflect different aspects of the data they draw. There are a variety of ways to do this:

• Symbolize a layer using graduated symbols, proportional symbols, graduated colors, or unclassed colors to show quantitative differences in features.
• Symbolize a layer using unique values to show qualitative difference in features.
• Control the size, rotation, color, or transparency, in addition to their primary symbology.
• Extrude features to 3D symbols.
• Control the customization of specific aspects of symbols by connecting individual symbol properties to feature attributes. You do this by enabling attribute-driven symbology for the entire layer.

Enable attribute-driven symbology

You can enable a feature layer to leverage attribute-driven symbology to connect symbol properties to attributes in the data. Once enabled, the symbol properties of the symbols in this layer, which can be connected to a feature attribute, are shown with the No attribute mapping defined button .

Tip:

A layer that includes a symbol with a procedural layer always has attribute-driven symbology enabled.

Learn about procedural symbol layers

1. In the Contents pane, highlight a feature layer.
2. Under Feature Layer, on the Appearance tab, in the Drawing group, click Symbology.
3. In the Symbology pane, on the Vary symbology by attribute tab , check Allow symbol property connections.

   You can now attach feature attributes to certain properties of the symbols within this layer. These attributes show the No attribute mapping defined button next to them.

Caution:

Connecting many properties to attributes can slow draw performance because many unique symbols have to be rendered. However, this is mostly incurred in the first drawing of the layer, as display caching will be used in subsequent draws. Consider setting limits on when the layer draws (scale-based in 2D or distance-based in 3D) to minimize this impact.

Connect symbol properties to attributes

Once a layer has been enabled for attribute-driven symbology, you can connect most symbol properties to the value in a feature attribute field or on an expression.

Tip:

When you are in the Format Symbol mode of the Symbology pane, click the menu button to ensure that Allow symbol property connections is checked, indicating that the layer is enabled for attribute-driven symbology. If this option is checked and disabled, one or more properties are already connected for this layer.

Symbol properties can only be connected to matching field types and values. Size properties require numeric fields with values greater than 0. If type conversion or multiple values are necessary, write an expression. See Attribute driven color in symbology for detailed information about connecting color properties.

1. In the Contents pane, highlight a feature layer.
2. Under Feature Layer, on the Appearance tab, in the Drawing group, click Symbology.
3. In the Symbology pane, click a symbol to modify.
4. In the Format Symbol mode of the Symbology pane, click the Properties tab and click the Layers tab .
5. Click the No attribute mapping defined button next to the property to be mapped to an attribute.
6. On the Set Attribute Mapping dialog box, choose an attribute field. The values in this field are used as the symbol property value for each feature.

   Click the Set an expression button to write an expression in the Arcade language.

   Tip:

   To set the image of a picture marker symbol layer to an attribute, the images must be stored in either a raster or a BLOB field. Consider storing these in an attachments table, joining the table to the feature class, and specifying the attachment field for the symbology.

7. Click OK to close the Set Attribute Mapping dialog box.

   appears next to the property to indicate that it is connected to an attribute. Hover over this icon to see the field or expression that is being used or to modify it further.

8. Click Apply in the Symbology pane to apply the changes.

Each feature is drawn with a customized symbol where the attribute value is applied as a symbol property value.

Review and update attribute-driven symbology

Once you have defined attribute-driven symbology for a layer, you can review and update the settings on a summary page for the layer.

1. In the Contents pane, highlight a feature layer.
2. Under Feature Layer, on the Appearance tab, in the Drawing group, click Symbology.
3. In the Symbology pane, the Vary symbology by attribute tab , expand the symbol groups as necessary to review the connected properties.
   • To connect to a different property, choose a different field from the drop-down menu. Choosing NONE disconnects the property from attribution.
   • To disconnect a property, hover over it and click the delete button , or choose NONE from the menu.
   • To go to the corresponding portion of the symbol where a connected property is set, click the Layers tab .