按名称对列表项进行分组

Question

我有一个包含重复项目的列表。我需要按相同的顺序对它们进行分组。

我在 LINQ 中找到了很多基于某些键对列表项进行分组的解决方案。

例如：-

我有如下列表

tbl1

tbl1

tbl2

tbl3

tbl1

tbl4

tbl2

我需要像下面这样分组

tbl1

tbl1

tbl1 

tbl1

tbl2

tbl2

tbl3

tbl4

这能实现吗。

Answer 1

您不需要分组，您想要更改列表的顺序。C# 使用该Sort()方法自然地内置了此功能。根据您的问题，我假设您userList的是List<string>. 既然如此，直接使用代码：userList.Sort();但是，假设您userList是 a List<SomeObject>，您可以通过以下方式使用 Linq 执行此操作：假设你的对象是这样的：class MyObject{&nbsp; &nbsp; public string Name;&nbsp; &nbsp; // Whatever other properties}你可以使用：var userList = new List<MyObject>();// Whatever extra code...userList = userList.OrderBy(v => v.Name).ToList();希望能解决问题！

Answer 2

你说你想对它们进行分组，但你给出的例子表明你需要对它们进行排序。如果你想删除重复的项目，你需要：var groupedCustomerList = userList&nbsp; &nbsp; .GroupBy(u => u.GroupID)&nbsp; &nbsp; .ToList();但是，如果您需要按照示例所示对它们进行排序，则需要编写如下内容：var groupedCustomerList = userList&nbsp; &nbsp; .OrderBy(u => u.GroupID)&nbsp; &nbsp; .ToList();要么var groupedCustomerList = userList.Sort();

Answer 3

您可以直接使用 GroupBy() 方法。List<string> elements = new List<string>() //lets consider them as strings{&nbsp; "tbl1",&nbsp; "tbl1",&nbsp; "tbl2",&nbsp; "tbl3",&nbsp; "tbl1",&nbsp; "tbl4",&nbsp; "tbl2"};var groups = elements.OrderBy(x=>x).GroupBy(x => x);//group them according to their valueforeach(var group in groups){&nbsp; foreach (var el in group) Console.WriteLine(el);}

Answer 4

Group您可以借助以下内容扩展s SelectMany：&nbsp; &nbsp;var groupedCustomerList = userList&nbsp; &nbsp; &nbsp;.GroupBy(u => u.GroupID)&nbsp; &nbsp; &nbsp;// Grouping&nbsp; &nbsp; &nbsp;.SelectMany(group => group)&nbsp; // Expand groups back (flatten)&nbsp; &nbsp; &nbsp;.ToList();这是怎么回事：initial:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {tbl1, tbl1, tbl2, tbl3, tbl1, tbl4, tbl2}after GroupBy:&nbsp; &nbsp; {Key = "1", {tbl1, tbl1, tbl1}},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {Key = "2", {tbl2, tbl2}},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {Key = "3", {tbl3}},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {Key = "4", {tbl4}},after SelectMany: {tbl1, tbl1, tbl1, tbl2, tbl2, tbl3, tbl4}