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Pie Chart

The Pie chart, as part of the ASP NET AJAX Chart, displays the data as sectors from a circle and is therefore useful for displaying data as parts of a whole.The Pie chart displays a single series of data in a two-dimensional circle. This help article shows which properties to use to customize a Pie chart (Figure 1) and shows sample code (Example 1) to create one.

Figure 1: A Pie chart with one item exploded.


You can customize a Pie chart:

  • The color is controlled via the BackgroundColor property of the PieSeriesItem.

  • The name that is shown in the legend is set via the Name property of the series items. You can hide the series items from the legend either by omitting it, or by setting the VisibleInLegend property to false.

  • Whether the sector is separated from the rest of the circle is controlled via the Exploded property of the PieSeriesItem. The Pie chart and the Donut chart are the only chart types in whose context the Exploded property is meaningful and will have effect.

  • The size of a segment of the Pie is controlled by its Y property of the PieSeriesItem and its relation to the other items' value.

    Only positive values have meaning in the context of a Pie chart and the developer must make sure that only positive value data is passed to the chart.

  • Each item can have a label and a tooltip that follow the common pattern defined in the DataFormatString property of the LabelsAppearance and TooltipsAppearance sections of the series.The format string uses the Y of the item. You can also load custom text from data source fields in labels and tooltips by using the composite ClientTemplate property.

  • The title, background colors and legend are controlled via the inner properties of the RadHtmlChart control and are common for all charts.You can find more information on the matter is available in the Server-side API and in the Element structure articles.

The Pie chart from Figure 1 was created with the code in Example 1.

Example 1: Creating the simple Pie chart in Figure 1 using hard coded data.

<telerik:RadHtmlChart runat="server" ID="PieChart1" Transitions="true">
            <telerik:PieSeries StartAngle="90">
                <LabelsAppearance Position="OutsideEnd" DataFormatString="{0} %" />
                <TooltipsAppearance DataFormatString="{0} %" />
                    <telerik:PieSeriesItem BackgroundColor="Purple" Exploded="true" Name="Internet Explorer" Y="18.3" />
                    <telerik:PieSeriesItem BackgroundColor="Orange" Exploded="false" Name="Firefox" Y="35.8" />
                    <telerik:PieSeriesItem BackgroundColor="Green" Exploded="false" Name="Chrome" Y="38.3" />
                    <telerik:PieSeriesItem BackgroundColor="Blue" Exploded="false" Name="Safari" Y="4.5" />
                    <telerik:PieSeriesItem BackgroundColor="Red" Exploded="false" Name="Opera" Y="2.3" />
    <ChartTitle Text="Browser Usage for April 2012">

The Pie chart does not have axes as they are not applicable in its context.

Currently the RadHtmlChart supports only one Pie series per chart. Adding more than one will result in overlapping charts and an extended legend.

See Also

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