Overview

A Radar Chart, sometimes referred to as a Spider Chart or Star Chart, is a circular graph used primarily as a data comparison tool. These charts normally have a circular shape, but can also be displayed as a polygon.

Unlike most other chart types, the Radar chart does not plot an X Value. Radar Chart X Values are ignored for all Radar Chart series. However, even though X Values are ignored, the X Axis is still used for the labels around the chart, as well as spacings between the label, and the chart itself.

Figure 1: A Radar Chart with a Circular shape.

The shape of the Radar Chart Area (which is the white area in the chart images) is determined by the custom attribute, AreaDrawingStyle. You can set the value of this custom attribute to one of two values including: Circle which is the default, or Polygon. The Circle shape is shown in Figure 1 above, and the Polygon shape is shown in Figure 2 below.

Figure 2: A polygon Radar chart using the Circular label style.

Example Setting the Drawing Style

Example

This sample demonstrates the syntax used to set the drawing style of the chart.

Visual Basic	Copy Code
Imports Dundas.Charting.WebControl ... ' The syntax used to set the drawing style. Chart1.Series("Series1")("AreaDrawingStyle")="Polygon"

C#	Copy Code
using Dundas.Charting.WebControl; ... // The syntax used to set the drawing style. Chart1.Series["Series1"]["AreaDrawingStyle"]="Polygon";

Radar Chart Drawing Styles

There are three main styles used to draw the Radar chart. These styles are defined by RadarDrawingStyle custom attribute, which can be set to any one of the following three values including: Area, Line, and Marker. When a series of this type is drawn, you have control over the appearance of the series by using its series properties. This means that the series drawing styles such as Borders, and Markers may also be used. Use the standard properties of the series, and point object including the MarkerStyle, MarkerColor, BorderColor, CorderWidth properties to adjust the appearance.

Figure 3: The marker style of Radar chart.

Example

This example demonstrates how to set the RadarDrawingStyle to show markers.

Visual Basic	Copy Code
Imports Dundas.Charting.WebControl ... ' Set to show markers. Chart1.Series("Series1")("RadarDrawingStyle")="Marker"

C#	Copy Code
using Dundas.Charting.WebControl; ... // Set to show markers. Chart1.Series["Series1"]["RadarDrawingStyle"]="Marker";

Radar Chart 3D Appearance

The Radar Circular chart area does not support real 3D. The only property from the Area3DStyle object that affects the Radar chart is the Enable3D property. By setting Enable3D to true, the drawing style of the area background changes to give the appearance of looking down on a 3D cone. No rotation, or any other 3D properties are applicable.

Figure 4: A 3D Radar chart.

Radar Chart Label Style

The displaying of labels around the Radar Chart is done using the CircularLabelsStyle custom attribute. Possible values for the CircularLabelsStyle attribute are shown in the table immediately following.

Figure 5: A Radar chart using radial label style.

Example

This example demonstrates how to set the appearance properties of the Radar chart. In this  case we are setting the CircularLabelStyle attribute to Radial.

Visual Basic	Copy Code
Imports Dundas.Charting.WebControl ... ' Setting the CircularLabelStyle to Radial. Chart1.Series("Series1")("CircularLabelStyle")="Radial"

C#	Copy Code
using Dundas.Charting.WebControl; ... // Setting the CircularLabelStyle to Radial. Chart1.Series["Series1"]["CircularLabelStyle"]="Radial";

The textual value for the axis labels can be explicitly set for the Radar chart using the AxisLabel property for each data point. Alternatively, custom axis labels may be defined using the CustomLabels collection of the X axis. If custom labels are set, they have higher priority over any other labels. When using custom axis labels, only the Text property of the custom label, and its index in the collection are important. The To and From properties are ignored.

The X axis object can also be used to control the distance between the chart area, and its circular labels by changing the X axis MajorTickmark.Size property.

Example

This example demonstrates how to set the tick mark size property using the MajorTickMark.Size attribute.

Visual Basic	Copy Code
Imports Dundas.Charting.WebControl ... ' Setting the major tick mark size to a value of 5. Chart1.ChartAreas("Default").AxisX.MajorTickMark.Size = 5

C#	Copy Code
using Dundas.Charting.WebControl; ... // Setting the major tick mark size to a value of 5. Chart1.ChartAreas["Default"].AxisX.MajorTickMark.Size = 5;

Radar Chart Limitations

When using the Radar Chart, it is worthwhile to note that there is no support for StripLines, nor is there any support for Cursors, Zooming or Scrolling.

See Also