CustomAggregateFunction.Calculate(GroupInfo) Method

Calculates the aggregated values of the specified series point value group.

Namespace: DevExpress.XtraCharts

Assembly: DevExpress.XtraCharts.v23.2.dll

NuGet Package: DevExpress.Charts

Declaration

C#

public abstract double[] Calculate(
    GroupInfo groupInfo
)

VB.NET

Public MustOverride Function Calculate(
    groupInfo As GroupInfo
) As Double()

Parameters

Name	Type	Description
groupInfo	GroupInfo	Information about values that should be aggregated.

Returns

Type	Description
Double[]	The array of data point values.

Remarks

The group info stores the following value collections in its properties:

Property	Value Levels
GroupInfo.Values1	Value (for common and the bubble series), Value_1 (for range series), High (for financial series)
GroupInfo.Values2	Weight (for the bubble series), Value_2 (for range series), Low (for financial series)
GroupInfo.Values3	Open (for financial series)
GroupInfo.Values4	Close (for financial series)

Example

Follow the steps below to create an aggregate function.

• Create a class that inherits the CustomAggregateFunction class.

• Implement its CustomAggregateFunction.Calculate method that then is called for each unique argument. Its groupInfo parameter is an object of the GroupInfo class and contains information about the argument and corresponding values:

  Property	Value Type
  groupInfo.Values1	Value (for common and bubble series), Value_1 (for range series), Low (for financial series)
  groupInfo.Values2	Weight (for bubble series), Value_2 (for range series), High (for financial series)
  groupInfo.Values3	Open (for financial series)
  groupInfo.Values4	Close (for financial series)

• Initialize the ScaleGridOptionsBase.CustomAggregateFunction property with an object of the newly created class.

• Set the ScaleGridOptionsBase.AggregateFunction property to Custom.

Form1.cs

private void Form1_Load(object sender, EventArgs e) {
    Series series = chartControl.Series["Random Data"];
    series.DataSource = GenerateData(100_000);
    series.ArgumentDataMember = "Argument";
    series.ValueDataMembers.AddRange("Value", "Value", "Value", "Value");

    XYDiagram diagram = chartControl.Diagram as XYDiagram;
    diagram.AxisX.DateTimeScaleOptions.AggregateFunction = AggregateFunction.Custom;
    diagram.AxisX.DateTimeScaleOptions.CustomAggregateFunction = new OhlcAggregateFunction();
}

class OhlcAggregateFunction : CustomAggregateFunction {
    public override double[] Calculate(GroupInfo groupInfo) {
        double open = groupInfo.Values1.First();
        double close = groupInfo.Values1.Last();
        double high = Double.MinValue;
        double low = Double.MaxValue;
        foreach (double value in groupInfo.Values1) {
            if (high < value) high = value;
            if (low > value) low = value;
        }

        return new double[] { high, low, open, close };
    }
}

Form1.vb

Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    Dim series As Series = chartControl.Series("Random Data")
    series.DataSource = GenerateData(100_000)
    series.ArgumentDataMember = "Argument"
    series.ValueDataMembers.AddRange("Value", "Value", "Value", "Value")

    Dim diagram As XYDiagram = TryCast(chartControl.Diagram, XYDiagram)
    diagram.AxisX.DateTimeScaleOptions.AggregateFunction = AggregateFunction.Custom
    diagram.AxisX.DateTimeScaleOptions.CustomAggregateFunction = New OhlcAggregateFunction()
End Sub

Private Class OhlcAggregateFunction
    Inherits CustomAggregateFunction

    Public Overrides Function Calculate(ByVal groupInfo As GroupInfo) As Double()
        Dim open As Double = groupInfo.Values1.First()
        Dim close As Double = groupInfo.Values1.Last()
        Dim high As Double = Double.MinValue
        Dim low As Double = Double.MaxValue
        For Each value As Double In groupInfo.Values1
            If high < value Then
                high = value
            End If
            If low > value Then
                low = value
            End If
        Next value

        Return New Double() { high, low, open, close }
    End Function
End Class