Unique values symbolize qualitative categories of values. Examples include habitat types, planning zones, voting preferences, and soil classifications. Unique value symbology can be based on one or more attribute fields in the dataset, or you can write an Arcade expression to generate values on which to symbolize.
There are two view modes to the Symbology pane when drawing with Unique Values symbology as follows:
- The Label view is where you manage the symbol, the values, the descriptive labels, and grouping of the symbol classes.
- The Scale Range view is where you specify the scale ranges in which each symbol class draws.
To symbolize using unique values, complete the following steps:
- Select a feature layer in the Contents pane. On the Appearance tab, in the Drawing group, click Symbology and click Unique Values to open the Symbology pane.
- In the Symbology pane, in the Field 1 menu, choose a field on which to symbolize.
- Optionally click the expression button to open the Expression Builder dialog box. Write an expression and click Verify to validate it.
- Optionally click Add Field to add additional symbol permutations. You can have up to three symbology fields. Only the first field can use an expression.
- Choose a color scheme. Depending on the number of unique values, the color schemes from project styles are filtered so that only relevant color schemes are presented to you. For example, if you have only five unique values, you see quantitative color schemes showing five colors. In addition, you can also choose from random color schemes. Check Show all to see all available color schemes. Color schemes stored in your Favorites style or custom styles always appear in this list, regardless of their type or number of colors. Click Format color scheme to modify a scheme.
- Optionally click Add all values . When choosing a field for unique values for the first time, no values are added.
Modify unique value symbology
You make most changes to unique value symbology from the Label view . You can modify unique value symbology as follows:
- To edit symbols, click a symbol in the Symbol column of the table to open the Format Symbol pane to modify the symbol or choose a different symbol.
- To edit the symbol class label, click the label in the Label column and type a new label.
- To change the order of the symbol classes, drag a symbol class row to a new position in the table or click Move selected value(s) up or Move selected value(s) down . To sort values, right-click the Value or Label heading and click Sort Ascending or Sort Descending . The symbol class order is reflected in the Contents pane and also in legends on layouts.
- To remove a symbol class, right-click the symbol class and click Remove . No data is deleted, but the associated features do not draw. Note that they may still be symbolized by an All other values group at the bottom of the table that collectively draws all values that are not otherwise symbolized by a symbol class.
- To remove the All other values collective group so that only features participating in symbol classes are drawn, click More and uncheck Show all other values.
- To add additional symbol classes, click Add values to open a table in the Select values to add subpane. This table lists all values not currently symbolized. Click Options and click Add new value to type a new value.
- To combine symbol classes, select the symbol class rows from the table while pressing the Ctrl key. Right-click and click Group values to combine selected classes into one group. Ungroup a grouped class by right-clicking it and clicking Ungroup values .
- To organize symbol classes into headings, right-click a symbol class and click Move value and click To group. Click New group to create a new heading. To change the name, click the heading title <heading>. Headings are reflected in the Contents pane and also in legends on layouts.
Vary unique value symbology by transparency, rotation, or size
In addition to specifying qualitative symbology with unique values, you can also symbolize additional attributes by varying the transparency, rotation, and size of the unique value symbols. While all of these treatments can be applied simultaneously, be aware that too many visual variations make the layer difficult to interpret. It is advisable to apply secondary symbology sparingly.
- In the Symbology pane, click the menu button and click Vary symbology by attribute.
- Expand Transparency, Rotation, or Size. In the case of polygon features, expand Outline width instead of Size.