Method IntersectBy
IntersectBy<TSource, TKey>(IEnumerable<TSource>, IEnumerable<TSource>, Func<TSource, TKey>)
Produces the set intersection of two sequences according to a specified key selector function.
Declaration
public static IEnumerable<TSource> IntersectBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector)Parameters
| Type | Name | Description |
|---|---|---|
| IEnumerable<TSource> | first | An IEnumerable<T> whose distinct elements that also appear in |
| IEnumerable<TSource> | second | An IEnumerable<T> whose distinct elements that also appear in the first sequence will be returned. |
| Func<TSource, TKey> | keySelector | A function to extract the key for each element. |
Returns
| Type | Description |
|---|---|
| IEnumerable<TSource> | A sequence that contains the elements that form the set intersection of two sequences. |
Type Parameters
| Name | Description |
|---|---|
| TSource | The type of the elements of the input sequences. |
| TKey | The type of key to identify elements by. |
Remarks
This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its `GetEnumerator` method directly or by using `foreach` in Visual C# or `For Each` in Visual Basic.
The intersection of two sets A and B is defined as the set that contains all the elements of A that also appear in B, but no other elements.
When the object returned by this method is enumerated, `Intersect` yields distinct elements occurring in both sequences in the order in which they appear in first.
The default equality comparer, Default, is used to compare values.
Exceptions
| Type | Condition |
|---|---|
| ArgumentNullException |
|
IntersectBy<TSource, TKey>(IEnumerable<TSource>, IEnumerable<TSource>, Func<TSource, TKey>, IEqualityComparer<TKey>?)
Produces the set intersection of two sequences according to a specified key selector function.
Declaration
public static IEnumerable<TSource> IntersectBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? keyComparer)Parameters
| Type | Name | Description |
|---|---|---|
| IEnumerable<TSource> | first | An IEnumerable<T> whose distinct elements that also appear in |
| IEnumerable<TSource> | second | An IEnumerable<T> whose distinct elements that also appear in the first sequence will be returned. |
| Func<TSource, TKey> | keySelector | A function to extract the key for each element. |
| IEqualityComparer<TKey> | keyComparer | An IEqualityComparer<T> to compare keys. |
Returns
| Type | Description |
|---|---|
| IEnumerable<TSource> | A sequence that contains the elements that form the set intersection of two sequences. |
Type Parameters
| Name | Description |
|---|---|
| TSource | The type of the elements of the input sequences. |
| TKey | The type of key to identify elements by. |
Remarks
This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its `GetEnumerator` method directly or by using `foreach` in Visual C# or `For Each` in Visual Basic.
The intersection of two sets A and B is defined as the set that contains all the elements of A that also appear in B, but no other elements.
When the object returned by this method is enumerated, `Intersect` yields distinct elements occurring in both sequences in the order in which they appear in first.
If keyComparer is null, the default equality comparer, Default, is used to compare values.
Exceptions
| Type | Condition |
|---|---|
| ArgumentNullException |
|