Question

我正在尝试编号列表的编号组。例如，这个LINQ查询给出了我想要的内容

(from word in "The quick brown fox jumps over the lazy dog" .Split()
group word by word.Length into w
select w)
.Select((value, index) => new { i = index + 1, value })
.SelectMany(
sm => sm.value,
(sm, s) => new { sm.i, s})

1 The 
1 fox 
1 the 
1 dog 
2 quick 
2 brown 
2 jumps 
3 over 
3 lazy

但我决定优化这个查询：为什么我们需要使用外部的SelectMany索引，如果它在SelectMany的第4次重载中有自己的索引？我尝试以下一种方式使用此重载，但我没有看到解决方案。

(from word in "The quick brown fox jumps over the lazy dog".Split()
           group word by word.Length into w
           select w)
                .SelectMany(
                (source, index) => ??????,
                (msource, coll) => ??????)

Answer 1

SelectMany的{p> This overload应该有效：

(from word in "The quick brown fox jumps over the lazy dog".Split()
 group word by word.Length into g
 select g)
.SelectMany((g, i) => g.Select(word => new { index = i + 1, word }))

在SelectMany LINQ中使用索引

1 个答案: