C# 如何将具有相同类型项目的列表列表合并为单个项目列表？
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How to merge a list of lists with same type of items to a single list of items?
提问by David.Chu.ca
The question is confusing, but it is much more clear as described in the following codes:
这个问题令人困惑，但如以下代码所述，它更加清晰：
List<List<T>> listOfList;
// add three lists of List<T> to listOfList, for example
/* listOfList = new {
{ 1, 2, 3}, // list 1 of 1, 3, and 3
{ 4, 5, 6}, // list 2
{ 7, 8, 9} // list 3
};
*/
List<T> list = null;
// how to merger all the items in listOfList to list?
// { 1, 2, 3, 4, 5, 6, 7, 8, 9 } // one list
// list = ???
Not sure if it possible by using C# LINQ or Lambda?
不确定是否可以使用 C# LINQ 或 Lambda？
Essentially, how can I concatenate or "flatten" a list of lists?
本质上，我如何连接或“展平”列表列表？
采纳答案by JaredPar
Use the SelectMany extension method
使用 SelectMany 扩展方法
list = listOfList.SelectMany(x => x).ToList();
回答by IRBMe
Do you mean this?
你是这个意思吗？
var listOfList = new List<List<int>>() {
new List<int>() { 1, 2 },
new List<int>() { 3, 4 },
new List<int>() { 5, 6 }
};
var list = new List<int> { 9, 9, 9 };
var result = list.Concat(listOfList.SelectMany(x => x));
foreach (var x in result) Console.WriteLine(x);
Results in: 9 9 9 1 2 3 4 5 6
结果是： 9 9 9 1 2 3 4 5 6
回答by Joe Chung
Here's the C# integrated syntax version:
这是 C# 集成语法版本：
var items =
from list in listOfList
from item in list
select item;
回答by Arman McHitarian
For List<List<List<x>>>and so on, use
对于List<List<List<x>>>等等，使用
list.SelectMany(x => x.SelectMany(y => y)).ToList();
This has been posted in a comment, but it does deserves a separate reply in my opinion.
这已发布在评论中，但在我看来确实值得单独回复。
