Bins are one way to aggregate point features in a map to observe patterns at small- and large-scale levels and to improve performance or comprehension.
When drawing features with bins, you can display the layer with polygon bins at smaller scales and individual point features at larger scales. The layer draws with bins at smaller scales by default. To see individual point features at all scales and not draw bins at all, you can turn off bin drawing. All binning settings are persisted if you turn bin drawing off. To adjust whether bins are drawn, on the Binning tab, in the Layer group, click Binning . For more information about modifying the bin display settings, see Work with binned feature layers.
You can change the way bins are displayed from the ribbon, but the way the bins and points are symbolized is controlled from the Symbology pane. The symbology of the bins is controlled independently from the symbology of the point features, and the table of contents shows both types of symbology for the layer.
Symbolize binned feature layers
The polygon bins in a binned feature layer can be symbolized with either single symbol or unclassed colors symbology. With unclassed colors symbology, the bin's symbol is based on the total feature count by default, but you can choose a different summary statistic to symbolize instead. To learn more, see Calculate summary statistics for bins.
In addition to single symbol or unclassed colors symbology, you can further refine the symbology of the bins by varying the size of the bin outlines by an attribute or expression or symbolizing features uniquely by deriving symbol property values from feature attributes. You cannot import and apply symbology from another layer to the bins of a binned feature layer, but you can do so for the underlying features.
The bin shape is determined by changing the Bin Type drop-down menu on the Binning tab. This setting is not editable when database-driven feature binning is used.
To change the symbology of a binned feature layer, follow these steps:
- Select a point feature layer in the Contents pane that is enabled for binning.
- If necessary, on the Feature Layer tab, in the Drawing group, click the Aggregation drop-down menu and choose Binning .
- On the Binning tab, in the Drawing group, click Symbology .
- In the Symbology pane, there are two available subtabs:
- Features—Symbolize the individual point features. Point features are drawn only at larger scales, or at all scales when bin drawing is disabled.
- Bins—Symbolize the polygon bins. Bins are drawn only at smaller scales, when bin drawing is enabled.
- Click the Bins tab. On the Primary symbology tab , choose a symbology from the drop-down list. Choose from single symbol or unclassed colors symbology. Edit the summary field and color scheme settings as needed.
- Optionally, click the Vary by symbology attribute tab to symbolize additional fields.
When adding a binned feature layer to a legend, both features and bins display unless the option to only show features visible in the map extent is checked.
Customize the value range of the bin levels
With unclassed colors symbology, the value range of the bins' symbology is set by default to two standard deviations from the mean of the summary field on a normal distribution curve. Sometimes, the summarized values of the bins are very similar, so the bins draw in similar colors on the map. You may want to further explore the data variance by setting a custom value range for the bins' symbology.
When a different standard deviation is selected, bins with a summarized value that is outside the range of the bin levels draw with the lowest or highest symbol of the set color scheme. You may want to choose a smaller standard deviation if the sample variance is small but you want to symbolize the full range of values.
The value range of the bin levels can be customized only when the layer is configured to use database-driven binning.
To adjust the value range of the bin levels, follow these steps:
- In the Symbology pane, on the Bins tab, click the Primary symbology tab .
- Click the Value range calculation drop-down menu. Choose a standard deviation calculation method.
- Adjust as desired.
You can also choose Custom, which allows you to customize the value range and specify the minimum and maximum value per level of detail. For reference, the layer's current level of detail is shown in the Level column of the table.
If your binned feature layer has a definition query set, is configured with ranges, or is time aware, changing the range or time period shown updates the map but not the symbology range. To refresh the symbology, in the Symbology pane, click the More drop-down menu and choose to refresh the values.
Use text to display bin values
You can add text to each bin to show the value of the statistic being symbolized. For example, if you are symbolizing bins of earthquakes based on mean magnitude, you can add text to each bin to show the actual mean magnitude for the features in that bin. Since bins are not actual features, this is not achieved with standard labeling techniques. Instead, the bin symbology template includes a shape marker symbol layer enabled for attribute-driven symbology to show the value of each bin. The value displayed by the symbol layer updates dynamically when the level of detail changes or if you change the summary field.
To display bin values, follow these steps:
- If bins are symbolized using unclassed colors, in the Symbology pane, under the Bins tab, on the Primary symbology tab , click the Template symbol. If bins are symbolized using single symbol symbology, click the symbol.
- In the Format Polygon Symbol pane, on the Properties tab, click the Layers tab .
- Check the box to display the shape marker (text) symbol.
- With the shape marker symbol layer highlighted, expand Appearance. On the Text string line, hover over the database button next to the text string to see the statistic or expression currently expressed by the text.
- To create an expression, click the database button , and in the Set Attribute Mapping window, click Set an expression .
If changes are made to the text string expression, it must be updated manually whenever the summary field is changed.
- In the expression builder, click OK to save any changes.
- Optionally, adjust the appearance of the shape marker symbol text or text string, and click Apply.