Enumerable.GroupBy<TSource, TKey, TResult> Method (IEnumerable<TSource>, Func<TSource, TKey>, Func<TKey, IEnumerable<TSource>, TResult>, IEqualityComparer<TKey>)
Silverlight
Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The keys are compared by using a specified comparer.
Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)
public static IEnumerable<TResult> GroupBy<TSource, TKey, TResult>( this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TKey, IEnumerable<TSource>, TResult> resultSelector, IEqualityComparer<TKey> comparer )
Type Parameters
- TSource
The type of the elements of source.
- TKey
The type of the key returned by keySelector.
- TResult
The type of the result value returned by resultSelector.
Parameters
- source
- Type: System.Collections.Generic.IEnumerable<TSource>
An IEnumerable<T> whose elements to group.
- keySelector
- Type: System.Func<TSource, TKey>
A function to extract the key for each element.
- resultSelector
- Type: System.Func<TKey, IEnumerable<TSource>, TResult>
A function to create a result value from each group.
- comparer
- Type: System.Collections.Generic.IEqualityComparer<TKey>
An IEqualityComparer<T> to compare keys with.
Return Value
Type: System.Collections.Generic.IEnumerable<TResult>A collection of elements of type TResult where each element represents a projection over a group and its key.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<TSource>. When you use instance method syntax to call this method, omit the first parameter.For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
Community Additions
ADD
Show: