private void btn_save_Click(object sender, EventArgs e)
        {
            var list = (from row in radGridView1.Rows
                        where (bool)row.Cells["?"].Value
                        select Guid.Parse((string)row.Cells["GUID"].Value)).ToList();

            if (list.Count == 0)
            {
                return;
            }

            var selection = _corpus.ToSelection().Create(list, "output");
            var exporter  = new ExporterCec6();

            exporter.Export(selection, @"tweets.cec6");

            Close();
        }
        private static Selection[] GetDateClusters(CorpusAdapterWriteDirect corpus)
        {
            var select       = corpus.ToSelection();
            var blockCluster = select.CreateBlock <SelectionClusterBlock>();

            blockCluster.ClusterGenerator = new SelectionClusterGeneratorDateTimeYearMonthDayOnlyValue();
            blockCluster.MetadataKey      = "Datum";
            blockCluster.Calculate();
            return(blockCluster.GetSelectionClusters().OrderBy(x => x.Displayname).ToArray());
        }