Class breaks rendering

Class breaks rendering can be used to symbolize layers that allow configuration of symbology. This includes ArcGIS Server feature layers, tables from Spatial Data Service endpoints, geoRSS layers, graphics layers, and SharePoint lists. For more information on the different layer types and their capabilities, see Layer types.

About class breaks

Class breaks are simply categories, each with a minimum and maximum value. When applied to a set of data, class breaks divide the data into categories based on the value of a certain field or attribute. Since the definition of a class depends on having a minimum and maximum value, class breaks are only applicable to numeric attributes. A class breaks renderer maps each class to a particular symbol. Graphics with similar values for the attribute get the same symbol.

As an example, suppose you have a buildings layer with an attribute that specifies the year each building was built. You want to symbolize buildings constructed since the year 2000 in green, buildings constructed between 1980 and 2000 in yellow, and buildings built before 1980 with red. Suppose that the earliest a building represented in the layer was constructed is 1960. In this case, you would define classes of 1960–1979, 1980–1999, and 2000–2012.

Configuring a class breaks renderer

The ArcGIS Map Web Part makes it simple to apply class breaks rendering to a layer. To do so, follow these steps:

  1. Choose the layer you want to configure class breaks for from the Map Contents panel. For instructions, see The Map Contents panel.
  2. On the Symbols tab of the ribbon, expand the Renderer drop-down menu and choose Class Breaks. The ArcGIS Map Web Part automatically calculates five class breaks for the first numeric field in the layer:

    Class Breaks selection on Renderer drop-down menu

  3. Configure the renderer:
    • Changing the attribute—To change the field on which the symbols are based, expand the Attribute drop-down menu and click the desired field:

      Attribute selected

    • Configuring class breaks—Options for modifying class breaks are provided on the Scheme Options dialog box. Click the Scheme Options button on the Symbols tab of the ribbon:

      Scheme Options button

      The Scheme Options dialog box appears:

      Scheme Options dialog box

Scheme options dialog box

The following options are available on the Scheme Options dialog box:

  • Changing the renderer and attribute—As with the drop-down menus on the ribbon, the renderer and attribute used can also be changed by selecting items from the Renderer and Attribute drop-down menus on the dialog box.
  • Changing the number of classes—To change the number of classes, type the desired number in the text box next to the Classes label, or use the Up and Down arrows next to the number.
  • Changing the color scheme—Just as you can on the ribbon, you can select a color scheme from the Scheme Options dialog box.
  • Selecting a class's symbol—To specify the symbol for one class, click the symbol to the left or the Down arrow to the right of the class's value range. Then choose the desired symbol from the symbol picker:

    Symbol picker

  • Modifying a class's symbol—To modify the symbol used by a class, first select the class on the right side of the dialog box. Then use the controls in the Current Symbol section of the dialog box to adjust the symbol's size, color, and transparency.

    The size and color controls that are enabled vary depending on the geometry type of the selected layer. For further information about specifying a symbol's size and color, see Single symbol rendering. The number of transparency sliders enabled also varies depending on the geometry type of the selected layer. For line and point layers, only one slider is enabled. In this case, the enabled slider determines the transparency of the entire symbol. For polygon layers, both sliders are enabled. The top slider determines the transparency of the symbol's fill, while the bottom slider determines the transparency of the symbol's border.

  • Changing a class's value range—The minimum and maximum values of a class can be changed by clicking a value and typing a new value:

    Class value range selector