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LINQ 2 Objects Having clause

开发者 https://www.devze.com 2023-02-27 14:44 出处:网络
Given a collection of MyType { int Index, string Name } what would be the technically efficient way of getting Min/Max index items?

Given a collection of MyType { int Index, string Name } what would be the technically efficient way of getting Min/Max index items?

we use:

MyType minIndexItem = items.Single(t=>
   t.Index == items.Min(t=>
      t.Index));

which doesn't look exactly elegant. We'd like to stick 开发者_Python百科to lambda syntax too and we are looking for the most technically efficient approach, not sugar'ish things like extension methods etc.

Thanks.


It could be

  (from item in items select item order by item.Index).First() 

Pretty fast if the Index field has a db index.


Sorting it will be the simple way to do it for LINQ-to-RDBMS, but probably not for LINQ-to-Objects, because the sorting may be expensive and runs in O(nlogn).

You can use LINQ aggregation to get the lowest or highest. This runs through the entire collection exactly once, an is always O(n). For example, to get the lowest item:

items.Aggregate((current, next) => next.Index < current.Index ? next : current);
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