C# 如何使用 Linq 对每 N 行进行分组
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How to use Linq to group every N number of rows
提问by RBear
I cannot find a way to make this work and hoping someone has an idea. A simplified example would be having a list of say integers 1-100, i want to group every 3 rows so the result would be 1,2,3 in first group then 4,5,6 in next group etc. I know how to get every nth record but what I need is all the records so I can then aggregate them, using first, last, sum, max, etc.
我找不到使这项工作的方法，并希望有人有想法。一个简化的例子是有一个整数 1-100 的列表，我想每 3 行分组，所以结果将是第一组中的 1,2,3 然后下一组中的 4,5,6 等等。我知道如何获取每第 n 条记录，但我需要的是所有记录，以便我可以使用 first、last、sum、max 等聚合它们。
Thanks!
谢谢！
采纳答案by idursun
var q = Enumerable.Range(0, 100).GroupBy(x => x/3);
Am I missing something?
我错过了什么吗？
回答by Scott Ivey
This example should work for querying non-numeric collections. It projects an index into the object to be grouped, and then removes it again during the grouping.
这个例子应该适用于查询非数字集合。它将索引投影到要分组的对象中，然后在分组过程中再次将其删除。
var studentQuery2 = students
.Select((student, index) => new {student, index})
.GroupBy(g => g.index / 3, i => i.student);
回答by Sudeep
How about a simpler approach:
一个更简单的方法怎么样：
var index = 0;
var grpOf3s = students.GroupBy(x => index++ / 3);
Update:If you are using the Keyvalue of the group item then you will need to convert the group enumerable to a list. Otherwise you will get a different Keyevery time it is accessed.
更新：如果您使用的Key是组项的值，则需要将组可枚举转换为列表。否则Key每次访问都会得到不同的结果。
var index = 0;
var grpOf3s = students.GroupBy(x => index++ / 3).ToList();
