具有许多值列的数据透视表 C#

Question

我找到了这个link

那里的代码可以使用数据透视值和数据透视列对数据表进行透视。我需要的是基于日期旋转并保留所有其他值列，如下所示：

Date Column1 Column2 Column3
2010   10      20      30
2011   40      50      60

到这里，我将列名作为第一行以及它们在年份下的值：

          2010  2011 
Column1    10    40
Column2    20    50
Column3    30    60

这是我现在的代码：

DataTable Pivot(DataTable dt, DataColumn pivotColumn, DataColumn pivotValue) {
    // find primary key columns 
    //(i.e. everything but pivot column and pivot value)
    DataTable temp = dt.Copy();
    temp.Columns.Remove( pivotColumn.ColumnName );
    temp.Columns.Remove( pivotValue.ColumnName );
    string[] pkColumnNames = temp.Columns.Cast<DataColumn>()
        .Select( c => c.ColumnName )
        .ToArray();

    // prep results table
    DataTable result = temp.DefaultView.ToTable(true, pkColumnNames).Copy();
    result.PrimaryKey = result.Columns.Cast<DataColumn>().ToArray();
    dt.AsEnumerable()
        .Select(r => r[pivotColumn.ColumnName].ToString())
        .Distinct().ToList()
        .ForEach (c => result.Columns.Add(c, pivotColumn.DataType));

    // load it
    foreach( DataRow row in dt.Rows ) {
        // find row to update
        DataRow aggRow = result.Rows.Find(
            pkColumnNames
                .Select( c => row[c] )
                .ToArray() );
        // the aggregate used here is LATEST 
        // adjust the next line if you want (SUM, MAX, etc...)
        aggRow[row[pivotColumn.ColumnName].ToString()] = row[pivotValue.ColumnName];
    }

    return result;
}

如何使用多个列值实现此结果？

Answer 1

我认为您需要采取稍微不同的方法，因为您的旋转方式略有不同。这是一个只接受表格和pivotColumnName 的方法。其他一切都使用输入表计算出来。

DataTable Pivot(DataTable table, string pivotColumnName)
{
    // TODO make sure the table contains at least two columns

     // get the data type of the first value column
    var dataType = table.Columns[1].DataType;

    // create a pivoted table, and add the first column
    var pivotedTable = new DataTable();
    pivotedTable.Columns.Add("Row Name", typeof(string));

    // determine the names of the remaining columns of the pivoted table
    var additionalColumnNames = table
        .AsEnumerable()
        .Select(x => x[pivotColumnName].ToString());

    // add the remaining columns to the pivoted table
    foreach (var columnName in additionalColumnNames)
        pivotedTable.Columns.Add(columnName, dataType);

    // determine the row names for the pivoted table
    var rowNames = table.Columns
        .Cast<DataColumn>()
        .Select(x => x.ColumnName)
        .Where(x => x != pivotColumnName);

    // fill in the pivoted data
    foreach (var rowName in rowNames)
    {
        // get the value data from the appropriate column of the input table
        var pivotedData = table
            .AsEnumerable()
            .Select(x => x[rowName]);

        // make the rowName the first value
        var data = new object[] { rowName }
            .Concat(pivotedData)
            .ToArray();

        // add the row
        pivotedTable.Rows.Add(data);
    }

    return pivotedTable;
}

这是我用来测试的：

var dateColumn = new DataColumn("Date", typeof(int));
var column1 = new DataColumn("Column1", typeof(int));
var column2 = new DataColumn("Column2", typeof(int));
var column3 = new DataColumn("Column3", typeof(int));
var table = new DataTable();
table.Columns.Add(dateColumn);
table.Columns.Add(column1);
table.Columns.Add(column2);
table.Columns.Add(column3);
table.Rows.Add(new object[] { 2010, 10, 20, 30 });
table.Rows.Add(new object[] { 2011, 40, 50, 60 });
var pivotedTable = Pivot(table, "Date");