Unclassed colors symbology is similar to graduated colors in that it's used to make choropleth maps. While graduated colors symbology distributes data into discrete classes with unique symbols, unclassed colors symbology distributes a color scheme evenly across features.
Unclassed color symbology can be based on an attribute field in the dataset, or you can write an Arcade expression to generate numeric values to symbolize on.
- Select a feature layer in the Contents pane.
- On the Appearance tab, in the Drawing group, click Symbology and click Unclassed Colors.
The Symbology pane appears.
- On the Symbology pane, choose the numeric field for the data to be mapped, or write an expression.
To use an expression, click to open the Expression Builder dialog box. Write an expression and click Verify to validate it. Note that although an expression is valid, it may not return a valid numeric value. You can filter the Expression Builder dialog box to show only numeric fields to help prevent this.
- To normalize the data, choose a field from the Normalization menu. Normalization is available only when the unclassed color symbology is based on a field. If it is symbolized based on an expression, the Normalization field is disabled.
- Choose a color scheme. Only continuous color schemes are shown by default. Check Show all to show all available color schemes. Color schemes stored in your Favorites style or custom styles always appear in this list, regardless of their type.
Modify unclassed colors
- To adjust the distribution of the color scheme, drag either of the slider controls on the histogram. Any data with a value greater than the maximum slider value draws with the color shown above it. Any data with a value lower than the minimum slider value draws with the color shown below it. Any variation in the color scheme is applied to the data between these two controls.
- To reverse the values, click More, and click Reverse values.
- To reverse the color scheme, click More, and click Reverse color scheme.
- To edit the symbols, click the Template or the Outline symbols to open the Format Symbol pane to modify them or choose different ones. When symbolizing point and line features, you work with a template symbol. When symbolizing polygon features, you work with the outline of the polygon.
- To control how the legend for this layer is labeled, edit the Upper label and the Lower label. By default, they are the minimum and maximum values of the symbol field.
- To format the labels, click and click Advanced. Expand Format Labels.
- To change the maximum sample size, click and click Advanced. Expand Sample Size and modify the Maximum sample size value. This is the maximum number of records considered when the data is classified. Limiting the sample size you improve performance, but may inadvertently omit important outliers in the dataset. Generally, the larger the dataset, the larger the sample size you should use.
- To show null values, click More, and click Show null values. Expand the Null values heading to specify the symbol and the legend label and legend description. If the attribute field used to define the unclassed color symbols includes null values, no symbol draws for those features unless you explicitly choose to draw them with a dedicated symbol.
Vary unclassed color symbology by transparency, rotation, or size
In addition to symbolizing by unclassed colors, you can also symbolize additional attributes by varying the transparency, rotation, and size of the symbols. The rotation variable is only available for point features. While all of these treatments can be applied simultaneously, be aware that too many visual variations make the layer very difficult to interpret. It is advisable to apply secondary symbology sparingly.
- On the Symbology pane, click and click Vary symbology by attribute.
- Expand Transparency, Rotation, or Size. In the case of polygon features, expand Outline width instead of Size.