使用linq和ToLookup()保留值的顺序 [英] Preserve order of values with linq and ToLookup()

问题描述

虽然我可以肯定从linq的ToLookup方法返回时键是无序的，但是否保留了值的顺序?我找不到任何一种说明方式的文件.

While I'm pretty certain that the keys are unordered when returned from linq's ToLookup method, Is the order of values preserved? I can't find any documentation that says one way or the other.

推荐答案

ToLookup()的当前实现确实确实保留了值的顺序(请检查Lookup<TKey,TElement>.Grouping<TKey,TElement>.Add()的实现)，但是我不认为可以保证保持这种方式.为了保证排序，最好的选择是使用Select的带有索引的超载，然后再次排序.

The current implementation of ToLookup() does indeed preserve the order of the values (check the implementation of Lookup<TKey,TElement>.Grouping<TKey,TElement>.Add()), but I do not believe it is guaranteed to stay that way. To guarantee ordering, your best bet is probably to include the element's original index, perhaps using Select's with-index overload, and then sort again.

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