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.
- In the Symbology pane, on the Primary symbology tab , 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 color symbology
From the Primary symbology tab , on the Classes tab you can do the following:
- 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.
- When symbolizing point and line feature layers, you can modify the template symbol and the color of it is set by the unclassed symbology. When symbolizing polygon feature layers, you can modify with the outline of the polygon and the color of the fill is set by the unclassed symbology. Click the Template symbol (for point and line feature layers) or the Outline symbol (for polygon feature layers) to open the Format Symbol pane to modify these symbols or choose different ones.
- PRIM 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 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.
From the Advanced symbol options tab you can do the following:
- To format the labels, expand Format labels.
- To change the maximum sample size, expand Sample size. 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 set up masking per feature, expand Feature level masking.
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 the Vary symbology by attribute tab .
- Expand Transparency, Rotation, or Size. In the case of polygon features, expand Outline width instead of Size.