30 lines
1.2 KiB
Markdown
30 lines
1.2 KiB
Markdown
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---
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title: GroupBy
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---
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# GroupBy
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Group elements from the dataset using a given condition.
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The `GroupBy` returns an [`IGrouping`](https://docs.microsoft.com/pt-BR/dotnet/api/system.linq.igrouping-2?view=netframework-4.7.2) containing each group defined by the given condition.
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### Signature
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```csharp
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Function GroupBy(Of TSource, TKey) ( _ source As IQueryable(Of TSource), _ keySelector As Expression(Of Func(Of TSource, TKey)) _ ) As IQueryable(Of IGrouping(Of TKey, TSource))
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```
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## Example
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```csharp
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var fruits = new List<Fruit>() {
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new Fruit() { Id = 1, Name = "Orange", Color = "Orange", Quantity = 3 },
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new Fruit() { Id = 2, Name = "Strawberry", Color = "Red", Quantity = 12 },
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new Fruit() { Id = 3, Name = "Grape", Color = "Purple", Quantity = 25 },
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new Fruit() { Id = 4, Name = "Pineapple", Color = "Yellow", Quantity = 1 },
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new Fruit() { Id = 5, Name = "Apple", Color = "Red", Quantity = 5 },
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new Fruit() { Id = 6, Name = "Mango", Color = "Yellow", Quantity = 2 }
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};
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// Sum quantity by color
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var byColor = fruits.GroupBy(g => g.Color).ToDictionary(k => k.Key, v => v.Sum(x => x.Quantity)); // { Orange = 3, Red = 17, Purple = 25, Yellow = 3 }
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```
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