اختصار اسطر من datatable من خلال مقارنة خلايا من datarows

DataTable maindataTable = new DataTable();
DataTable SecdataTable = new DataTable();
//***********************************************************************************************************

private void ShowTurnByTurnDirections(Collection<RouteSegment> roads, Collection<Feature> features)
{

maindataTable.Locale = CultureInfo.InvariantCulture;

maindataTable.Columns.Add("RoadName");
maindataTable.Columns.Add("Direction");
maindataTable.Columns.Add("Length(Meter)", typeof(object));


for (int i = 0; i < roads.Count; i++)
{
DataRow dataRow = maindataTable.NewRow();
dataRow["RoadName"] = features.ColumnValues["FENAME"];
dataRow["Direction"] = roads.DrivingDirection;
dataRow["Length(Meter)"] = Math.Round(((LineBaseShape)features.GetShape()).GetLength(GeographyUnit.DecimalDegree, DistanceUnit.Meter), 2);
maindataTable.Rows.Add(dataRow);
}
dgridDirections.DataSource = maindataTable;
}

public void btnFilter_Click(object sender, EventArgs e)
{
SecdataTable.Locale = CultureInfo.InvariantCulture;

//SecdataTable.Columns.Add("RoadName");
//SecdataTable.Columns.Add("Direction");
//SecdataTable.Columns.Add("Length(Meter)");

if (maindataTable.Rows.Count > 1)
{

SecdataTable = maindataTable.Copy();
DataColumn[] SecDColume = new DataColumn[SecdataTable.Columns.Count];
DataRow[] SecDRows = new DataRow[SecdataTable.Rows.Count];
//for (int i = 1; i < SecdataTable.Rows.Count; i++)
//{
// for (int j = 1; i < SecdataTable.Columns.Count; i++)
// {
// if (SecDRows[SecDColume] = "Forword" && SecDRows + 1[SecDColume] = "Forword")
// {

// }
// }

//}


//DataRow[] SecDRows = new DataRow[SecdataTable.Rows.Count];
//DataColumn[] SecDColum = new DataColumn[SecdataTable.Rows.Count];
//for (int i = 1; i < maindataTable.Rows.Count; i++)
//{
// string[] x;
// string[] y;
// double[] z;

// SecDColum[2] = z;
// z = SecDColum;
//if (Y['1'] =="")
//{ }
//else
//{ }
//}
//dataRow["RoadName"] = features.ColumnValues["FENAME"];
//dataRow["Direction"] = roads.DrivingDirection;
//dataRow["Length(Meter)"] = Math.Round(((LineBaseShape)features.GetShape()).GetLength(GeographyUnit.DecimalDegree, DistanceUnit.Meter), 2);
//maindataTable.Rows.Add(dataRow);

// maindataTable.Rows.CopyTo(MainDRows, 0);
// DataRow[] SecDRows = new DataRow[maindataTable.Rows.Count];
// MainDRows.CopyTo(SecDRows, 0);

// {

// SecdataTable.Rows.Add(SecDRows);

//}
dgridDirections.DataSource = SecdataTable;
}
else
MessageBox.Show("No Data to filter!");
}

}