AutomaticTimeSpanScaleOptions.CustomAggregateFunction Property

Gets or sets the custom aggregate function callback that calculates the aggregated values.

Namespace: DevExpress.Xpf.Charts

Assembly: DevExpress.Xpf.Charts.v24.1.dll

NuGet Package: DevExpress.Wpf.Charts

Declaration

C#

[Browsable(false)]
public CustomAggregateFunction CustomAggregateFunction { get; set; }

VB.NET

<Browsable(False)>
Public Property CustomAggregateFunction As CustomAggregateFunction

Property Value

Type	Description
CustomAggregateFunction	The custom aggregate function callback.

Remarks

Do the following to create an aggregate function:

• Set the AggregateFunction property to Custom.

• Develop a class that inherits the CustomAggregateFunction class.

• Override the CustomAggregateFunction.Calculate(GroupInfo) method.

• Initialize the CustomAggregateFunction property with a newly created aggregate function class instance.

XAML

<Window
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:TimeSpanExample"
        xmlns:dxc="http://schemas.devexpress.com/winfx/2008/xaml/charts" 
        x:Class="TimeSpanExample.MainWindow"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Window.DataContext>
        <local:ChartViewModel/>
    </Window.DataContext>
    <Grid>
        <dxc:ChartControl>
            <dxc:XYDiagram2D>
                <!-- Series settings are skipped. -->
                <dxc:XYDiagram2D.AxisX>
                    <dxc:AxisX2D>
                        <dxc:AxisX2D.TimeSpanScaleOptions>
                            <dxc:AutomaticTimeSpanScaleOptions AggregateFunction="Custom">
                                <dxc:AutomaticTimeSpanScaleOptions.CustomAggregateFunction>
                                    <local:StandardDeviationAggregateFunction/>
                                </dxc:AutomaticTimeSpanScaleOptions.CustomAggregateFunction>
                            </dxc:AutomaticTimeSpanScaleOptions>
                        </dxc:AxisX2D.TimeSpanScaleOptions>
                    </dxc:AxisX2D>
                </dxc:XYDiagram2D.AxisX>
            </dxc:XYDiagram2D>
        </dxc:ChartControl>
    </Grid>
</Window>

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows;
using DevExpress.Xpf.Charts;

namespace TimeSpanExample {
    public class StandardDeviationAggregateFunction : CustomAggregateFunction {
        public override string ToString() {
            return "StdDev (Custom)";
        }
        public override double[] Calculate(GroupInfo groupInfo) {
            double sum = 0.0;
            foreach (double value in groupInfo.Values1) {
                sum += value;
            }
            int len = groupInfo.Values1.Count();
            double averageAmount = sum / len;
            double standardDeviationSquareSum = 0.0;
            foreach (double value in groupInfo.Values1) {
                double deviation = value - averageAmount;
                standardDeviationSquareSum += deviation * deviation;
            }
            double stdDev = Math.Sqrt(standardDeviationSquareSum / len);
            return new double[1] { stdDev };
        }
    }
}

VB.NET

Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Windows
Imports DevExpress.Xpf.Charts

Namespace TimeSpanExample
    Public Class StandardDeviationAggregateFunction
        Inherits CustomAggregateFunction

        Public Overrides Function ToString() As String
            Return "StdDev (Custom)"
        End Function

        Public Overrides Function Calculate(ByVal groupInfo As GroupInfo) As Double()
            Dim sum As Double = 0.0

            For Each value As Double In groupInfo.Values1
                sum += value
            Next

            Dim len As Integer = groupInfo.Values1.Count()
            Dim averageAmount As Double = sum / len
            Dim standardDeviationSquareSum As Double = 0.0

            For Each value As Double In groupInfo.Values1
                Dim deviation As Double = value - averageAmount
                standardDeviationSquareSum += deviation * deviation
            Next

            Dim stdDev As Double = Math.Sqrt(standardDeviationSquareSum / len)
            Return New Double(0) {stdDev}
        End Function
    End Class
End Namespace