需要索引的自定义类型的 DataTable

Question

正如标题所说，我需要对我的 DataTable 进行自定义排序，其中我使用 DataRow 的索引，结果应该是 EnumerableRowCollection 或 OrderedEnumerableRowCollection，因为我想要一个表（默认顺序）和一个 DataView（自定义顺序）。

我想要的顺序：首先按几列排序（例如姓名，姓氏，...）。然后拆分table1和table2中的表格（只是表格的一半）。然后交替从第一个和第二个表中选择。结果应该是

table1 的行
table2 的行
table1的行

原表不应该受到影响，结果应该是对原表的引用。

internal static DataView GetSortedView(this DataTable table)
{
    return table.GetSortedTable().AsDataView();
}

internal static void OrderedEnumerableRowCollection<DataRow> GetSortedTable(this DataTable table)
{

int half = table.Rows.Count / 2;
//sort columns by name for example
var enumerable = table.AsEnumerable().OrderBy(field => field.Field<string>("Name"), new NaturalStringComparer());

//here is the tricky part
enumerable= enumerable.OrderBy(row =>
                    {
                        int myIndex = ?; //I cannot use table.Rows.IndexOf(row) because the order of the current OrderedEnumerableRowCollection should be used and not the default order of the table

                        bool upperHalf = myIndex > half;
                        if (upperHalf)
                        {
                            myIndex -= half;
                        }

                        return new CustomSortItem(myIndex , upperHalf);
                    }, new CustomSort());
return enumerable;
}

我尝试先为索引添加一个新列，但这并没有真正起作用，因为当我尝试删除该列时，最后由于延迟加载而收到异常。

internal static void OrderedEnumerableRowCollection<DataRow> GetSortedTable(this DataTable table)
{

//create another column for an index
string tempSortName = "[TEMP_SORT]";
table.Columns.Add(tempSortName);

//sort columns by Name for example
var enumerable= table.AsEnumerable().OrderBy(field => field.Field<string>("Name"), new NaturalStringComparer());

//set the temporary order (index)
int count = 0;
foreach(DataRow row in enumerable)
{
    row[tempSortName] = count++;
}

//here is the tricky part
int half = table.Rows.Count / 2;
enumerable= enumerable.OrderBy(row =>
                    {
                        int myIndex = int.parse(row[tempSortName].ToString()); //exception here. column not found

                        bool upperHalf = myIndex  > half;
                        if (upperHalf)
                        {
                            myIndex  -= half;
                        }

                        return new CustomSortItem(myIndex , upperHalf);
                    }, new CustomSort());

                    table.Columns.Remove(tempSortName);
return enumerable;
}

我也不想使用 IEnumerable，因为当我创建 DataView 时，我必须创建另一个表才能创建一个，然后引用丢失（view.Table 不是原始表，只是没有参考）。

IEnumerable<DataRow> enumerable...
enumerable.CopyToDataTable().AsDataView();
// I have to call CopyToDataTable() in order to create a DataView

Answer 1

如果使用Select的两个参数版本按顺序计算行数呢？

enumerable = enumerable.Select((r, i) => new { r, i })
                       .OrderBy(ri => {
                            var upperHalf = ri.i > half;
                            var myIndex = ri.i - (upperHalf ? half : 0);
                            return new CustomSortItem(myIndex, upperHalf);
                        }, new CustomSort());

Answer 2

一段时间后，我找到了解决方案，GetSortedTable 和 GetSortedView 的解决方案不同（每个都有自己的解决方案）。如果有人有更好的解决方案，我将不胜感激。

internal static void DataView GetSortedView(this DataTable table)
{

   //create another column for an index
   string tempSortName = "[TEMP_SORT]";
   table.Columns.Add(tempSortName);

   //sort columns by Name for example
   var enumerable= table.AsEnumerable().OrderBy(field => field.Field<string>("Name"), new NaturalStringComparer());

   //set the temporary order (index)
   int count = 0;
   foreach(DataRow row in enumerable)
   {
       row[tempSortName] = count++;
   }

   //here is the tricky part
   int half = table.Rows.Count / 2;
   enumerable= enumerable.OrderBy(row =>
    {

      if (int.TryParse(row[tempSortName]?.ToString(), out int myIndex )) //everything here is triggered if row[tempSortName] is set... or before it is set... idk... wtf. so there is a new column but there are not any indices in it (or just one)
       {
         myIndex++;
         bool upperHalf = myIndex  > half;
         if (upperHalf)
         {
            myIndex  -= half;
         }
         return new CustomSortItem(myIndex , upperHalf);
       }
    }, new CustomSort());

   DataView view = enumerable.AsDataView();
   view.Table.Columns.Remove(tempSortName);

   return view;
}


internal static IEnumerable<DataRow> GetSortedTable(this DataTable table)
{
   IEnumerable<DataRow> result;
   //sort columns by Name for example
   var enumerable= table.AsEnumerable().OrderBy(field => field.Field<string>("Name"), new NaturalStringComparer());
   int half =  table.Rows.Count / 2;
   IEnumerable<DataRow> one = enumerable.Take(half);
   IEnumerable<DataRow> two = enumerable.Skip(half);
   result = one.InterleaveEnumerationsOfEqualLength(two);
   return result;
 }

internal static IEnumerable<DataRow> InterleaveEnumerationsOfEqualLength<DataRow>(this IEnumerable<DataRow> first, IEnumerable<DataRow> second)
{
   using (IEnumerator<DataRow> enumerator1 = first.GetEnumerator(), enumerator2 = second.GetEnumerator())
   {
      while (enumerator1.MoveNext() && enumerator2.MoveNext())
      {
         yield return enumerator1.Current;
         yield return enumerator2.Current;
      }
    }
}