C#•2y ago

❔ Get collection of a groupBy based on key.

I have a list of KeyValuePairs <ushort, ushort> I am attempting to group the list by the key,

so myNewCollection = list.OrderBy(k => k.key);

now we step into a foreach loop
foreach (var player in players)
{
     // TO DO : Get all items from myNewCollection where key is player.Id
      // Iterate new collection
}

so myNewCollection = list.OrderBy(k => k.key);

now we step into a foreach loop
foreach (var player in players)
{
     // TO DO : Get all items from myNewCollection where key is player.Id
      // Iterate new collection
}

csharp What I am having trouble with is understanding the proper, efficient way to get all items of myNewCollection where the key is my playerId.

10 Replies

Velcer•2y ago

I could just do inside my player loop, foreach (var item in list.Where(s => s.Key == player.Id)) However I believe that by first doing orderBy outside my player loop, I am limiting the overall amount of iterations or at least that is my hope. Correct me if I am wrong.

Saber•2y ago

ordering is going to be more inefficient than just applying a simple where filter.

Velcer•2y ago

I see. So it is most practical then to just have the where filter inside my player loop? There is perhaps no way to reduce the iterations more than that?

canton7•2y ago

ToLookup?

Saber•2y ago

you could convert that list to a lookup.

var lookup = list.ToLookup(x => x.Key);

var lookup = list.ToLookup(x => x.Key);

and accessing the list related to the player would be lookup[player.Id]

Velcer•2y ago

👀 I've never heard of this before Thank you!!

canton7•2y ago

(I take that back - missed you were looping over players)

Velcer•2y ago

The idea is to do an initial iteration for sorting, before my player loop ah, thank you. I think ToLookup is what I needed

canton7•2y ago

Yep

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Get collection of a groupBy based on key.