private void MenuFileOpen_Click(object sender, EventArgs e) { if (openFileDialog.ShowDialog(this) == DialogResult.OK) { string filename = openFileDialog.FileName; string extension = Path.GetExtension(filename); if (extension == ".xls" || extension == ".xlsx") { ExcelReader db = new ExcelReader(filename, true, false); TableSelectDialog t = new TableSelectDialog(db.GetWorksheetList()); if (t.ShowDialog(this) == DialogResult.OK) { DataTable tableSource = db.GetWorksheet(t.Selection); double[,] sourceMatrix = tableSource.ToMatrix(out sourceColumns); // Detect the kind of problem loaded. if (sourceMatrix.GetLength(1) == 2) { MessageBox.Show("Missing class column."); } else { this.dgvLearningSource.DataSource = tableSource; this.dgvTestingSource.DataSource = tableSource.Copy(); CreateScatterplot(graphInput, sourceMatrix); // enable "Start" button startButton.Enabled = true; } } } } }