扩展枢轴功能

Question

我已成功使用此示例代码。

public static Dictionary<TKey1, Dictionary<TKey2, TValue>> PivotLinq<TSource, TKey1,     TKey2, TValue>(
this IEnumerable<TSource> source, Func<TSource, TKey1> key1Selector, Func<TSource,    TKey2> key2Selector,
Func<IEnumerable<TSource>, TValue> aggregate)
{
return source.GroupBy(key1Selector).Select(
x => new
        {
            X = x.Key,
            Y = x.GroupBy(key2Selector).Select(
            z => new
            {
                Z = z.Key,
                V = aggregate(z)
            }
            ).ToDictionary(e => e.Z, o => o.V)
        }
        ).ToDictionary(e => e.X, o => o.Y);
    }

现在我已将其扩展如下：

public static Dictionary<TKey1,     Dictionary<TKey2,Dictionary<TKey3,Dictionary<TKey4,TValue>>>> PivotLinq<TSource, TKey1,    TKey2,TKey3,TKey4, TValue>(
this IEnumerable<TSource> source, Func<TSource, TKey1> key1Selector, Func<TSource, TKey2> key2Selector, Func<TSource, TKey3> key3Selector, Func<TSource, TKey4> key4Selector,
   Func<IEnumerable<TSource>, TValue> aggregate)
    {
        return source.GroupBy(key1Selector).Select(
        x => new
        {
            X = x.Key,
            Y = x.GroupBy(key2Selector).Select(
            z => new
            {
                Z = z.Key,
                V =z.GroupBy(key3Selector).Select(  // aggregate(z)
                 w => new 
                 {
                     W=w.Key ,
                     B = w.GroupBy(key4Selector).Select(
                      c=> new 
                      {
                          C=c.Key ,
                          D=aggregate(c)
                      }).ToDictionary(e=>e.C, o=>o.D)
                 }
                      ).ToDictionary(e=>e.W, o=>o.B)
            }
                 ).ToDictionary(e=>e.Z , o=>o.V  )
            }).ToDictionary(e=>e.X,o=>o.Y);

        }

但是，聚合函数不会产生所需的结果。有人能让我知道我哪里出错吗？