MoreEnumerableExceptByTSource, TKey Method (IEnumerableTSource, IEnumerableTSource, FuncTSource, TKey, IEqualityComparerTKey) |
Returns the set of elements in the first sequence which aren't
in the second sequence, according to a given key selector.
Namespace:
MoreLinq
Assembly:
MoreLinq (in MoreLinq.dll) Version: 3.0.0
Syntax public static IEnumerable<TSource> ExceptBy<TSource, TKey>(
this IEnumerable<TSource> first,
IEnumerable<TSource> second,
Func<TSource, TKey> keySelector,
IEqualityComparer<TKey> keyComparer
)
<ExtensionAttribute>
Public Shared Function ExceptBy(Of TSource, TKey) (
first As IEnumerable(Of TSource),
second As IEnumerable(Of TSource),
keySelector As Func(Of TSource, TKey),
keyComparer As IEqualityComparer(Of TKey)
) As IEnumerable(Of TSource)
public:
[ExtensionAttribute]
generic<typename TSource, typename TKey>
static IEnumerable<TSource>^ ExceptBy(
IEnumerable<TSource>^ first,
IEnumerable<TSource>^ second,
Func<TSource, TKey>^ keySelector,
IEqualityComparer<TKey>^ keyComparer
)
[<ExtensionAttribute>]
static member ExceptBy :
first : IEnumerable<'TSource> *
second : IEnumerable<'TSource> *
keySelector : Func<'TSource, 'TKey> *
keyComparer : IEqualityComparer<'TKey> -> IEnumerable<'TSource>
Parameters
- first
- Type: System.Collections.GenericIEnumerableTSource
The sequence of potentially included elements. - second
- Type: System.Collections.GenericIEnumerableTSource
The sequence of elements whose keys may prevent elements in
first from being returned. - keySelector
- Type: SystemFuncTSource, TKey
The mapping from source element to key. - keyComparer
- 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
- The type of the elements in the input sequences.
- TKey
- The type of the key returned by keySelector.
Return Value
Type:
IEnumerableTSourceA sequence of elements from
first whose key was not also a key for
any element in
second.
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 is a set operation; if multiple elements in first have
equal keys, only the first such element is returned.
This operator uses deferred execution and streams the results, although
a set of keys from second is immediately selected and retained.
See Also