public SimpleGroupTestViewModel()
{
_table1 = new ReactiveTable();
var groupColumn = new ReactiveColumn <string>(GroupColumnId);
_table1.AddColumn(groupColumn);
var valueColumn = new ReactiveColumn <int>(ValueColumnId);
_table1.AddColumn(valueColumn);
// ReactiveTable table2 = new ReactiveTable();
// table2.AddColumn(new ReactiveColumn<string>("GroupColumn2"));
// table2.AddColumn(new ReactiveColumn<int>("ValueColumn2"));
_groupedTable = new AggregatedTable(_table1);
_groupedTable.GroupBy <string>(groupColumn.ColumnId);
_groupedTable.AddAggregate(groupColumn, CountColumnId, () => new Count <string>());
_groupedTable.AddAggregate(valueColumn, SumColumnId, () => new Sum <int>());
_groupedTable.AddAggregate(valueColumn, AverageColumnId, () => new Average <int>());
_groupedTable.AddAggregate(valueColumn, MinColumnId, () => new Min <int>());
_groupedTable.AddAggregate(valueColumn, MaxColumnId, () => new Max <int>());
LoadDataCommand = new DelegateCommand(LoadData);
Items = new ObservableCollection <SimpleGroupItem>();
_groupedTable.RowUpdates().Subscribe(OnRowUpdate);
}