源数据 如图所示

// <summary>/// DataTable扩展 列转行方法（2*2矩阵转换）/// </summary>/// <param name="dtSource">数据源</param>/// <param name="columnFilter">逗号分隔 如SDateTime,PM25,PM10,O3,NO2,SO2,CO 第一个参数为行，其余为要转换的列</param>/// <returns></returns>public static DataTable PivotDatatableColToRow(this DataTable dtSource, string columnFilter){var columns = columnFilter.Split(',');DataTable dtFilter = dtSource.DefaultView.ToTable(false, columns);DataTable dtResult = new DataTable();var rowCount = dtFilter.Rows.Count;var columnCount = columns.Length;// 源数组的行数比DataTable的行数+1,, 加一行表头object[,] arrSource = new object[rowCount + 1, columnCount];// 目标数组的行数等于选择的列数,列数等于 源数据的行数+1, 加一列 属性名object[,] arrResult = new object[columnCount, rowCount + 1];// 原数组第一行写表头for (int i = 0; i < columnCount; i++){arrSource[0, i] = dtFilter.Columns[i].ColumnName;}// 源数据 每一行写 数据for (int i = 0; i < rowCount; i++){for (int j = 0; j < columnCount; j++){arrSource[i + 1, j] = dtFilter.Rows[i][j];}}// 原数 转置到 目标数组for (int i = 0; i < rowCount + 1; i++){for (int j = 0; j < columnCount; j++){arrResult[j, i] = arrSource[i, j];}}// 创建 Datatable 的结构for (int i = 0; i < rowCount + 1; i++){if (!dtResult.Columns.Contains(arrResult[0, i].ToString())) {dtResult.Columns.Add(arrResult[0, i].ToString());}}List<string> valueList = new List<string>();for (int i = 1; i < columnCount; i++){for (int j = 0; j < rowCount + 1; j++){valueList.Add(arrResult[i, j].ToString());}dtResult.Rows.Add(valueList.ToArray());valueList.Clear();}return dtResult;}

 转换后的数据

DataTable newdt = dt.AsEnumerable().Where(p => p.Field<string>("City") == "武汉").CopyToDataTable().PivotDatatableColToRow("SDateTime,PM25,PM10,O3,NO2,SO2,CO");