Chart symbology

A chart is a type of statistical graphic that represents data. Charts can be used as multivariate symbology in ArcGIS AllSource to show quantitative differences between attributes, with each part of the chart representing an attribute value that contributes to the overall whole set of values. Chart symbology can be used with point, line, or polygon features. For example, you can use pie chart symbols to represent the ethnicity of a district in a city. Each section of the pie chart comprises one of the ethnicities. Each chart symbol can then be sized proportionally by the district's total population.

Census tracts in New Orleans use pie chart symbols to show ethnicity percentage. The symbols are sized by total population.

Tip:

Chart symbology is most effective when mapping no more than 30 features on a 2D map. When you have more than 30 features, patterns on the map become difficult to determine. If you are mapping more than 30 features, consider using a different type of symbology.

Note:

The drawing of chart symbols is not supported in local and global scenes.

Draw a layer with chart symbols

To draw a layer with chart symbols, follow these steps:
1. Click a feature layer in the Contents pane.
2. On the Feature Layer tab, in the Drawing group, click the Symbology drop-down arrow .
3. Under Symbolize your layer by quantity, click Charts .

   The Symbology pane appears.

4. On the Primary symbology tab , click the Chart type drop-down menu and choose a chart type.
   • Bar Chart —Each feature attribute is symbolized with a vertical column or horizontal bar.
   • Pie Chart —Each feature attribute is represented as a section of a pie chart.
   • Stacked Chart —Each feature attribute is stacked on a single bar. Stacked chart symbols are best for displaying amounts by category.
5. On the Fields table, choose the numeric fields that you want to visualize in the chart symbol. Use the drop-down menu to add a field to the list.

   Note:

   Chart symbology does not support the use of custom expressions.

6. Optionally, click the Color Scheme drop-down menu to choose a color scheme for the chart symbols.

   A random color scheme is used by default. You can also double-click a symbol in the list to change its properties. For example, you may want to use transparency settings in Color Editor on all except one field so that the attribute is emphasized in the chart symbol.

   Note:

   The colors in the color scheme are applied to all symbol classes by default. To apply the color scheme to a subset of symbol classes only, select those classes by highlighting them in the table (press Shift or Ctrl while clicking in the Label column to select symbol classes). With symbol class rows selected, choose a color scheme from the drop-down list at the top of the Symbology pane.

7. Optionally, for bar or stacked chart symbols, choose a field from the Normalization menu. Choose percentage of total to divide the data value to create ratios or choose log to symbolize on the logarithm of each value.

   This allows you to generate a smaller range of values if the dataset includes significant outliers.

8. Click the Background symbol patch to set a background fill for polygon or line features. Choose a symbol from the gallery or adjust its structure or appearance on the Properties subtab.

Click the Clear Selection button to unselect symbol classes if necessary.

Modify chart field settings

Chart symbology allows you to display multiple fields in one symbol. Because of this, changes may be necessary to manage the complexity of the symbol. Additionally, some fields include values that must be effectively handled to improve symbolization of the data. For example, a pie chart symbol with slices that are too small to view can be grouped together, or data that contains negative values can be excluded from the chart symbol.

In the Symbology pane , on the Primary symbology tab , click the More menu to perform the following tasks:

• Click Show excluded values to manage the symbology of excluded values. You can set, apply, and modify an expression from the Advanced symbol options tab .
• For pie chart symbols only, click Use slice threshold to create a pie slice that combines any slice smaller than the threshold value into one slice for each pie chart. For example, if the slice threshold value is 5.0 percent, any slice in the pie chart that is below 5.0 percent is added to the threshold slice. This may be none, one, or many slices per pie chart symbol. When this option is active, you can modify the threshold value, symbol, and label from the Fields table, in the Slice Threshold subsection.
• For pie chart symbols only, click Show invalid values and choose a symbol to represent empty (null), zero, or negative values in the data. This symbol draws only when the value of every field in the pie chart symbol is invalid. When this option is active, you can modify its symbol and label from the Fields table, in the Other Values subsection.

To turn off the above options, click the More drop-down menu and click the option again.

You can also change the order of the fields after you add them to the Fields list. Press Shift while clicking to select one or more fields in the list and click Move selected field(s) up or Move selected value(s) down . You can also click More > Reverse field order to switch the order of the fields, or choose Reverse symbol order to reverse the colors assigned to your field symbols.

To remove one or more fields from the list, click Remove selected value(s) .

Modify chart symbols

In the Symbology pane, click a symbol to modify its appearance in the chart symbol. You can also modify a chart symbol's overall appearance in the expanded properties section in the lower half of the pane. You can enable and modify leader lines, add accent bars, specify chart spacing, and manage overlapping rules for chart symbols.

When symbolizing line and polygon layers with chart symbology, use the Draw chart symbols above all layers check box to control where the chart symbols fall in the draw order of the map. This option is not available when symbolizing point features.

• When checked, the chart symbols draw above all layers in the map, including annotation layers, regardless of the layer draw order specified in the Contents pane. Only labels draw above the chart symbols.
• When this option is unchecked, this layer respects the drawing order specified by the arrangement of layers in the Contents pane, with the chart symbols drawing above the polygon or line symbols in the layer. This choice ensures that annotation layers in the map are not obscured by chart symbols.

Set the chart symbol size

Use one or more fields in your data to change the chart symbol's size or set a fixed size for all chart symbols. Depending on the type of chart symbol, the following Appearance settings are available:

Chart type	Size option	Details
Bar Chart	Bar width	Sets the width of each bar chart symbol to the specified size.
	Maximum bar length	Determines the length of the bar for the feature with the highest value between all fields. The minimum bar length is always zero.
	Bar spacing	Sets the amount of space between bars. This cannot be less than zero.
Pie Chart	Size type: Fixed size Sum of selected fields Field	Determines how the size of the pie chart symbol is set. Fixed size maps all pie chart symbols at the same size. Sum of selected fields uses the sum of values from each field in the pie chart symbol to determine the size. Field varies the size of the pie chart symbol using field values. Choose the field from the attribute table, or write a custom expression, and optionally apply a normalization method.
	Size (Fixed size only)	Sets the fixed size of each pie chart symbol.
	Minimum size	Determines the size of the pie chart symbol with the smallest sum between all fields.
	Maximum size (Sum of selected fields and Field only)	If checked, sets a maximum size of the pie chart symbols. The largest value in a single field, an expression, or the largest sum between all fields is set to this size.
Stacked Chart	Length type: Fixed length Sum of selected fields	Determines how the length of the stacked chart symbol is set. Fixed length maps all stacked chart symbols at the same length. Sum of selected fields uses the sum of values from each field in the stacked chart symbol to determine the size.
	Length (Fixed length only)	Sets the length of each stacked chart symbol.
	Width	Sets the width of each stacked chart symbol.

For pie and stacked chart symbols, additional properties are available under the Appearance heading, depending on the Size type set.

• For pie chart symbols, where the Size type is set by a Field or the Sum of selected fields, check the Appearance compensation (Flannery) check box. This uses a drawing technique that adjusts symbol sizes upward to account for the underestimation of circular symbol sizes.

  Dive-in:

  There is a tendency for map readers to underestimate the size of proportional circles on maps, especially at the larger end of the size range. Appearance compensation uses an algorithm defined by James Flannery in which larger symbols are scaled up to compensate for this perception. You can use appearance compensation only when you have relatively sized pie chart symbols (proportionally sized with no unit specified) and no Maximum size specified.

• To add an outline to the chart symbol, check the Show chart outline check box and choose the desired Outline symbol from the gallery.

Use leader lines

Leader lines, also known as line callouts, are linear graphics that connect the feature in the map to its chart symbol. In areas of dense features, you may want to use leader lines to clearly show to which feature the chart symbol belongs. Other symbols, such as backgrounds and accent bars, can be added to the chart symbol to further emphasize the chart symbol and its leader line. By default, a leader line is drawn when the chart symbol cannot be placed at the centroid of the feature.

To change the appearance and placement of the leader line from the Symbology pane :

• Expand Leader lines on the Primary symbology tab .
• Click the Type drop-down menu and choose Background. This creates leader line symbols similar to lines used in background callouts.
• To prevent chart symbols from overlapping, check the Prevent chart overlap box. This is often necessary when using leader lines.

With the Background leader line type selected, you can make additional changes or add surrounds to the leader line symbol:

• Background symbol—Draws a background polygon symbol around the chart symbol. You can specify its color, outline color, and outline width or choose a symbol from the gallery.
• Accent bar symbol—Draws a line symbol (bar) tangentially to the edge of the chart symbol. You can specify the accent bar's color and width, or choose a symbol from the gallery.
• Leader line symbol—Defines the color, and width of the leader line symbol. You can specify the leader line's color and width, or choose a symbol from the gallery.
• Leader style—Choose from one of seven leader line styles, which control the way the leader line is drawn from the chart symbol to its feature.
• Leader tolerance—The closest distance the chart symbol can be from the center of the feature for the leader line to draw on the map.
• Gap—Defines the size of the gap between the leader line and the chart symbol.
• Margin—Defines the left, right, top, and bottom margins of space between the leader line and its chart symbol.

Set chart symbol display options

Additional functionality for chart symbols is available by expanding Display options on the Primary symbology tab.

• Orientation—The relative direction or position of the chart symbol.
  • Bar and stacked chart symbols can be oriented horizontally or vertically. Click the drop-down menu and choose Bar to set the bars horizontally; choose Column to set the bars vertically.
  • For pie chart symbols, a Clockwise orientation marks the first symbolized field at 90 degrees and displays fields in a clockwise manner. Counterclockwise marks the first field at 0 degrees and displays fields counterclockwise.

    Legacy:

    In ArcMap, pie chart symbol orientations are geographic (clockwise) or arithmetic (counterclockwise).

• Display in 3D—Check this check box to give chart symbols a 3D look. Use the bar sliders to change the Tilt (pie chart symbols only) or Thickness of the symbol.

Note:

Use tilt settings on pie chart symbols sparingly. Slices oriented toward the back of the pie appear smaller than they are, which may affect cartographic understanding of the data.

Add a size legend

In maps and layouts, the default legend displayed in the Contents pane comprises a preview image of the chart symbol, and the individual symbols for each included field. If you are using chart symbology and the size or length type of your chart symbols are set to a field or the sum of selected fields, you can also include a size legend.

1. In the Symbology pane , on the Primary symbology tab , expand Appearance.
2. Check the Show legend check box.
3. Adjust the Legend outline color and Legend leaderline color as needed.

The size legend shows the relative values of a small, medium, and large chart symbol only. It does not have a fill color, and the values cannot be edited. The size of the largest chart symbol depends on your size type properties.

Learn more about formatting legends