MoreEnumerableDistinctByTSource, TKey Method (IEnumerableTSource, FuncTSource, TKey, IEqualityComparerTKey) |
Returns all distinct elements of the given source, where "distinctness"
is determined via a projection and the specified comparer for the projected type.
Namespace:
MoreLinq
Assembly:
MoreLinq (in MoreLinq.dll) Version: 2.3.0
Syntax public static IEnumerable<TSource> DistinctBy<TSource, TKey>(
this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector,
IEqualityComparer<TKey> comparer
)
<ExtensionAttribute>
Public Shared Function DistinctBy(Of TSource, TKey) (
source As IEnumerable(Of TSource),
keySelector As Func(Of TSource, TKey),
comparer As IEqualityComparer(Of TKey)
) As IEnumerable(Of TSource)
public:
[ExtensionAttribute]
generic<typename TSource, typename TKey>
static IEnumerable<TSource>^ DistinctBy(
IEnumerable<TSource>^ source,
Func<TSource, TKey>^ keySelector,
IEqualityComparer<TKey>^ comparer
)
[<ExtensionAttribute>]
static member DistinctBy :
source : IEnumerable<'TSource> *
keySelector : Func<'TSource, 'TKey> *
comparer : IEqualityComparer<'TKey> -> IEnumerable<'TSource>
Parameters
- source
- Type: System.Collections.GenericIEnumerableTSource
Source sequence - keySelector
- Type: SystemFuncTSource, TKey
Projection for determining "distinctness" - comparer
- Type: System.Collections.GenericIEqualityComparerTKey
The equality comparer to use to determine whether or not keys are equal.
If null, the default equality comparer for TSource is used.
Type Parameters
- TSource
- Type of the source sequence
- TKey
- Type of the projected element
Return Value
Type:
IEnumerableTSourceA sequence consisting of distinct elements from the source sequence,
comparing them by the specified key projection.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type
IEnumerableTSource. When you use instance method syntax to call this method, omit the first parameter. For more information, see
Extension Methods (Visual Basic) or
Extension Methods (C# Programming Guide).
Remarks
This operator uses deferred execution and streams the results, although
a set of already-seen keys is retained. If a key is seen multiple times,
only the first element with that key is returned.
See Also