/// <summary>
/// Transpose transpose the table, i.e. exchange columns and rows
/// this can only work if all columns in the table are of the same type
/// </summary>
/// <param name="numberOfDataColumnsChangeToPropertyColumns">Number of data columns that are changed to property columns before transposing the table.</param>
/// <param name="numberOfPropertyColumnsChangeToDataColumns">Number of property columns that are changed to data columns before transposing the table.</param>
/// <returns>null if succeeded, error string otherwise</returns>
public virtual string Transpose(int numberOfDataColumnsChangeToPropertyColumns, int numberOfPropertyColumnsChangeToDataColumns)
{
numberOfDataColumnsChangeToPropertyColumns = Math.Max(numberOfDataColumnsChangeToPropertyColumns, 0);
numberOfDataColumnsChangeToPropertyColumns = Math.Min(numberOfDataColumnsChangeToPropertyColumns, this.DataColumnCount);
numberOfPropertyColumnsChangeToDataColumns = Math.Max(numberOfPropertyColumnsChangeToDataColumns, 0);
numberOfPropertyColumnsChangeToDataColumns = Math.Min(numberOfPropertyColumnsChangeToDataColumns, this.PropertyColumnCount);
// first, save the first data columns that are changed to property columns
Altaxo.Data.DataColumnCollection savedDataColumns = new DataColumnCollection();
Altaxo.Data.DataColumnCollection savedPropColumns = new DataColumnCollection();
Altaxo.Collections.IAscendingIntegerCollection savedDataColIndices = new Altaxo.Collections.IntegerRangeAsCollection(0, numberOfDataColumnsChangeToPropertyColumns);
Altaxo.Collections.IAscendingIntegerCollection savedPropColIndices = new Altaxo.Collections.IntegerRangeAsCollection(0, numberOfPropertyColumnsChangeToDataColumns);
// store the columns temporarily in another collection and remove them from the original collections
DataColumns.MoveColumnsTo(savedDataColumns, 0, savedDataColIndices);
this.PropertyColumns.MoveColumnsTo(savedPropColumns, 0, savedPropColIndices);
// now transpose the data columns
_dataColumns.Transpose();
savedDataColumns.InsertRows(0, numberOfPropertyColumnsChangeToDataColumns); // take offset caused by newly inserted prop columns->data columns into account
savedDataColumns.MoveColumnsTo(this.PropertyColumns, 0, savedDataColIndices);
savedPropColumns.RemoveRows(0, numberOfDataColumnsChangeToPropertyColumns); // take offset caused by data columns changed to property columns into account
savedPropColumns.MoveColumnsTo(this.DataColumns, 0, savedPropColIndices);
// now insert both the temporary stored DataColumnCollections at the beginning
return(null); // no error message
}