Hello Thomas,

I have been looking into your question and created a small sample with a XamDataGrid where only the sum summary result is shown for a summary field.

In order to achieve this programmatically, my suggestion is to format the summary value in the grid’s FieldLayoutInitialized event:

 private void xdg_FieldLayoutInitialized(object sender, Infragistics.Windows.DataPresenter.Events.FieldLayoutInitializedEventArgs e)
        {
            SummaryDefinition summary = new SummaryDefinition();
            summary.Calculator = SummaryCalculator.Sum;
            summary.SourceFieldName = "Number1";
            summary.Key = "Field1.1";
            summary.StringFormat = "{0:N0}";
            this.xdg.FieldLayouts[0].SummaryDefinitions.Add(summary);
        }

Additionally, you could check out this topic in our documentation regarding formatting the value of a Summary.

You can find the sample attached below. If you require any further assistance on the matter, please let me know.

Sincerely,

Bozhidara Pachilova

Associate Software Developer

4452.XDGSummaryStringFormat.zip