ArcGIS Pro 3.4 API Reference Guide
ArcGIS.Core.Data Namespace / TableStatisticsDescription Class / GroupBy Property
Example Version

GroupBy Property (TableStatisticsDescription)
Gets or sets a list of Fields to be used for GroupBy during statistics computation.
Syntax
public IReadOnlyList<Field> GroupBy {get; set;}
Exceptions
ExceptionDescription
The Field input at a specific index in theGroupBy list is null.
Remarks
If the underlying data store does not support SQL (e.g., shapefiles), GroupBy will have no effect on the outcome of the computation.
Example
Calculating Statistics on a Table
// Calculate the Sum and Average of the Population_1990 and Population_2000 fields, grouped and ordered by Region
public void CalculateStatistics(FeatureClass countryFeatureClass)
{
    using (FeatureClassDefinition featureClassDefinition = countryFeatureClass.GetDefinition())
    {
        // Get fields
        Field regionField = featureClassDefinition.GetFields()
          .First(x => x.Name.Equals("Region"));
        Field pop1990Field = featureClassDefinition.GetFields()
          .First(x => x.Name.Equals("Population_1990"));
        Field pop2000Field = featureClassDefinition.GetFields()
          .First(x => x.Name.Equals("Population_2000"));

        // Create StatisticsDescriptions
        StatisticsDescription pop1990StatisticsDescription = new StatisticsDescription(pop1990Field,
                  new List<StatisticsFunction>() { StatisticsFunction.Sum,
                                            StatisticsFunction.Average });

        StatisticsDescription pop2000StatisticsDescription = new StatisticsDescription(pop2000Field,
                  new List<StatisticsFunction>() { StatisticsFunction.Sum,
                                            StatisticsFunction.Average });

        // Create TableStatisticsDescription
        TableStatisticsDescription tableStatisticsDescription = new TableStatisticsDescription(new List<StatisticsDescription>() {
              pop1990StatisticsDescription, pop2000StatisticsDescription });
        tableStatisticsDescription.GroupBy = new List<Field>() { regionField };
        tableStatisticsDescription.OrderBy = new List<SortDescription>() { new SortDescription(regionField) };

        // Calculate Statistics
        IReadOnlyList<TableStatisticsResult> tableStatisticsResults = countryFeatureClass.CalculateStatistics(tableStatisticsDescription);

        foreach (TableStatisticsResult tableStatisticsResult in tableStatisticsResults)
        {
            // Get the Region name
            // If multiple fields had been passed into TableStatisticsDescription.GroupBy, there would be multiple values in TableStatisticsResult.GroupBy
            string regionName = tableStatisticsResult.GroupBy.First().Value.ToString();

            // Get the statistics results for the Population_1990 field
            StatisticsResult pop1990Statistics = tableStatisticsResult.StatisticsResults[0];
            double population1990Sum = pop1990Statistics.Sum;
            double population1990Average = pop1990Statistics.Average;

            // Get the statistics results for the Population_2000 field
            StatisticsResult pop2000Statistics = tableStatisticsResult.StatisticsResults[1];
            double population2000Sum = pop2000Statistics.Sum;
            double population2000Average = pop2000Statistics.Average;

            // Do something with the results here...
        }
    }
}
Requirements

Target Platforms: Windows 11, Windows 10

ArcGIS Pro version: 3 or higher.
See Also