C# 使用 SUM 和 ORDER BY 的 Linq 查询
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Linq Query with SUM and ORDER BY
提问by Mats
I have a (C#) class called Hit with an ItemID (int) and a Score (int) property. I skip the rest of the details to keep it short. Now in my code, I have a huge List on which I need to do the following select (into a new List): I need to get the sum of all Hit.Score's for each individual Hit.ItemID, ordered by Score. So if I have the following items in the original list
我有一个名为 Hit 的 (C#) 类，带有一个 ItemID (int) 和一个 Score (int) 属性。我跳过其余的细节以保持简短。现在在我的代码中，我有一个巨大的列表，我需要在上面执行以下选择（到一个新列表中）：我需要获取每个单独的 Hit.ItemID 的所有 Hit.Score 的总和，按分数排序。所以如果我在原始列表中有以下项目
ItemID=3, Score=5
ItemID=1, Score=5
ItemID=2, Score=5
ItemID=3, Score=1
ItemID=1, Score=8
ItemID=2, Score=10
the resulting List should contain the following:
结果列表应包含以下内容：
ItemID=2, Score=15
ItemID=1, Score=13
ItemID=3, Score=6
Can somebody help?
有人可以帮忙吗？
采纳答案by user95144
var q = (from h in hits
group h by new { h.ItemID } into hh
select new {
hh.Key.ItemID,
Score = hh.Sum(s => s.Score)
}).OrderByDescending(i => i.Score);
回答by Daniel Brückner
IEnumerable<Hit> result = hits.
GroupBy(hit => hit.ItemID).
Select(group => new Hit
{
ItemID = group.Key,
Score = group.Sum(hit => hit.Score)
}).
OrderByDescending(hit => hit.Score);
