プログラムで集計を追加

xmlns:ig="http://schemas.infragistics.com/xaml"
…
<Grid x:Name="LayoutRoot" Background="White">
   <ig:XamGrid x:Name="dataGrid" AutoGenerateColumns="False">
      <ig:XamGrid.SummaryRowSettings>
         <ig:SummaryRowSettings AllowSummaryRow="Top" SummaryScope="ColumnLayout">
         </ig:SummaryRowSettings>
      </ig:XamGrid.SummaryRowSettings>
      <ig:XamGrid.Columns>
         <ig:TextColumn Key="ProductID">
         <ig:TextColumn Key="ProductName">
            <ig:TextColumn.SummaryColumnSettings>
               <ig:SummaryColumnSettings>
                  <ig:SummaryColumnSettings.SummaryOperands>
                     <ig:CountSummaryOperand IsApplied="True">
                     </ig:CountSummaryOperand>
                     <ig:MaximumSummaryOperand>
                     </ig:MaximumSummaryOperand>
                     <ig:MinimumSummaryOperand>
                     </ig:MinimumSummaryOperand>
                  </ig:SummaryColumnSettings.SummaryOperands>
               </ig:SummaryColumnSettings>
            </ig:TextColumn.SummaryColumnSettings>
         </ig:TextColumn>
         …
      </ig:XamGrid.Columns>
   </ig:XamGrid>
</Grid>

Imports Infragistics.Controls.Grids
…
Dim DisplaySummary As Column = Me.MyDataGrid.Columns.DataColumns("ProductName")
DisplaySummary.SummaryColumnSettings.SummaryOperands(2).IsApplied = True

using Infragistics.Controls.Grids;
…
Column DisplaySummary = this.MyDataGrid.Columns.DataColumns["ProductName"];
DisplaySummary.SummaryColumnSettings.SummaryOperands[2].IsApplied = true;