Enumerable.Union 方法

定義

產生兩個序列的集合等位。Produces the set union of two sequences.

多載

Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)

使用預設相等比較值來比較值,以便產生兩個序列的集合等位。Produces the set union of two sequences by using the default equality comparer.

Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)

使用指定的 IEqualityComparer<T> 產生兩個序列的集合等位。Produces the set union of two sequences by using a specified IEqualityComparer<T>.

Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)

使用預設相等比較值來比較值,以便產生兩個序列的集合等位。Produces the set union of two sequences by using the default equality comparer.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TSource> ^ Union(System::Collections::Generic::IEnumerable<TSource> ^ first, System::Collections::Generic::IEnumerable<TSource> ^ second);
public static System.Collections.Generic.IEnumerable<TSource> Union<TSource> (this System.Collections.Generic.IEnumerable<TSource> first, System.Collections.Generic.IEnumerable<TSource> second);
static member Union : seq<'Source> * seq<'Source> -> seq<'Source>
<Extension()>
Public Function Union(Of TSource) (first As IEnumerable(Of TSource), second As IEnumerable(Of TSource)) As IEnumerable(Of TSource)

類型參數

TSource

輸入序列之項目的類型。The type of the elements of the input sequences.

參數

first
IEnumerable<TSource>

IEnumerable<T>,其獨特項目構成第一個等位集合。An IEnumerable<T> whose distinct elements form the first set for the union.

second
IEnumerable<TSource>

IEnumerable<T>,其獨特項目構成第二個等位集合。An IEnumerable<T> whose distinct elements form the second set for the union.

傳回

IEnumerable<TSource>

IEnumerable<T>,其中包含來自兩個輸入序列的項目,但不包括重複的項目。An IEnumerable<T> that contains the elements from both input sequences, excluding duplicates.

例外狀況

firstsecondnullfirst or second is null.

範例

下列程式碼範例示範如何使用 Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) 來取得兩個整數序列的聯集。The following code example demonstrates how to use Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) to obtain the union of two sequences of integers.

int[] ints1 = { 5, 3, 9, 7, 5, 9, 3, 7 };
int[] ints2 = { 8, 3, 6, 4, 4, 9, 1, 0 };

IEnumerable<int> union = ints1.Union(ints2);

foreach (int num in union)
{
    Console.Write("{0} ", num);
}

/*
 This code produces the following output:

 5 3 9 7 8 6 4 1 0
*/
' Create two arrays of integer values.
Dim ints1() As Integer = {5, 3, 9, 7, 5, 9, 3, 7}
Dim ints2() As Integer = {8, 3, 6, 4, 4, 9, 1, 0}

' Get the set union of the two arrays.
Dim union As IEnumerable(Of Integer) = ints1.Union(ints2)

' Display the resulting set's values.
Dim output As New System.Text.StringBuilder
For Each num As Integer In union
    output.AppendLine(num & " ")
Next
Console.WriteLine(output.ToString())

' This code produces the following output:
'
' 5 
' 3 
' 9 
' 7 
' 8 
' 6 
' 4 
' 1 
' 0 

如果您想要比較某些自訂資料類型的物件序列,您必須 IEquatable<T> 在 helper 類別中執行泛型介面。If you want to compare sequences of objects of some custom data type, you have to implement the IEquatable<T> generic interface in a helper class. 下列程式碼範例會示範如何在自訂資料類型和覆寫和方法中,執行這個介面 GetHashCode EqualsThe following code example shows how to implement this interface in a custom data type and override GetHashCode and Equals methods.

public class ProductA: IEquatable<ProductA>
{
    public string Name { get; set; }
    public int Code { get; set; }

    public bool Equals(ProductA other)
    {
        if (other is null)
            return false;

        return this.Name == other.Name && this.Code == other.Code;
    }

    public override bool Equals(object obj) => Equals(obj as ProductA);
    public override int GetHashCode() => (Name, Code).GetHashCode();
}
Public Class ProductA
    Inherits IEquatable(Of ProductA)

    Public Property Name As String
    Public Property Code As Integer

    Public Function Equals(ByVal other As ProductA) As Boolean
        If other Is Nothing Then Return False
        Return Me.Name = other.Name AndAlso Me.Code = other.Code
    End Function

    Public Overrides Function Equals(ByVal obj As Object) As Boolean
        Return Equals(TryCast(obj, ProductA))
    End Function

    Public Overrides Function GetHashCode() As Integer
        Return (Name, Code).GetHashCode()
    End Function

End Class

在您執行這個介面之後,您可以 ProductA 在方法中使用物件的順序 Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) ,如下列範例所示:After you implement this interface, you can use sequences of ProductA objects in the Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) method, as shown in the following example:

ProductA[] store1 = { new ProductA { Name = "apple", Code = 9 },
                       new ProductA { Name = "orange", Code = 4 } };

ProductA[] store2 = { new ProductA { Name = "apple", Code = 9 },
                       new ProductA { Name = "lemon", Code = 12 } };
Dim store1() As ProductA = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}}

Dim store2() As ProductA = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "lemon", .Code = 12}}
//Get the products from the both arrays
//excluding duplicates.

IEnumerable<ProductA> union =
  store1.Union(store2);

foreach (var product in union)
    Console.WriteLine(product.Name + " " + product.Code);

/*
    This code produces the following output:

    apple 9
    orange 4
    lemon 12
*/
' Get the products from the both arrays
' excluding duplicates.

Dim union = store1.Union(store2)

For Each product In union
    Console.WriteLine(product.Name & " " & product.Code)
Next

' This code produces the following output:
'
' apple 9
' orange 4
' lemon 12
' 

備註

這個方法是使用延後執行所執行。This method is implemented by using deferred execution. 立即傳回值是一個物件,它會儲存執行動作所需的所有資訊。The immediate return value is an object that stores all the information that is required to perform the action. 這個方法所表示的查詢不會執行,直到以 GetEnumerator foreach Visual c # 或 Visual Basic 中的方法來列舉物件為止 For EachThe 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.

這個方法會排除傳回集合中的重複專案。This method excludes duplicates from the return set. 這是方法的不同行為 Concat ,它會傳回輸入序列中的所有元素,包括重複專案在內。This is different behavior to the Concat method, which returns all the elements in the input sequences including duplicates.

預設的相等比較子 Default 會用來比較實作為泛型介面之類型的值 IEqualityComparer<T>The default equality comparer, Default, is used to compare values of the types that implement the IEqualityComparer<T> generic interface. 若要比較自訂資料類型,您需要執行這個介面,並為類型提供您自己的 GetHashCode Equals 方法。To compare a custom data type, you need to implement this interface and provide your own GetHashCode and Equals methods for the type.

列舉這個方法所傳回的物件時,會 Unionfirst second 該順序列舉和產生每個尚未產生的元素。When the object returned by this method is enumerated, Union enumerates first and second in that order and yields each element that has not already been yielded.

適用於

產品 推出的版本

Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)

使用指定的 IEqualityComparer<T> 產生兩個序列的集合等位。Produces the set union of two sequences by using a specified IEqualityComparer<T>.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TSource> ^ Union(System::Collections::Generic::IEnumerable<TSource> ^ first, System::Collections::Generic::IEnumerable<TSource> ^ second, System::Collections::Generic::IEqualityComparer<TSource> ^ comparer);
public static System.Collections.Generic.IEnumerable<TSource> Union<TSource> (this System.Collections.Generic.IEnumerable<TSource> first, System.Collections.Generic.IEnumerable<TSource> second, System.Collections.Generic.IEqualityComparer<TSource> comparer);
public static System.Collections.Generic.IEnumerable<TSource> Union<TSource> (this System.Collections.Generic.IEnumerable<TSource> first, System.Collections.Generic.IEnumerable<TSource> second, System.Collections.Generic.IEqualityComparer<TSource>? comparer);
static member Union : seq<'Source> * seq<'Source> * System.Collections.Generic.IEqualityComparer<'Source> -> seq<'Source>
<Extension()>
Public Function Union(Of TSource) (first As IEnumerable(Of TSource), second As IEnumerable(Of TSource), comparer As IEqualityComparer(Of TSource)) As IEnumerable(Of TSource)

類型參數

TSource

輸入序列之項目的類型。The type of the elements of the input sequences.

參數

first
IEnumerable<TSource>

IEnumerable<T>,其獨特項目構成第一個等位集合。An IEnumerable<T> whose distinct elements form the first set for the union.

second
IEnumerable<TSource>

IEnumerable<T>,其獨特項目構成第二個等位集合。An IEnumerable<T> whose distinct elements form the second set for the union.

comparer
IEqualityComparer<TSource>

用來比較值的 IEqualityComparer<T>The IEqualityComparer<T> to compare values.

傳回

IEnumerable<TSource>

IEnumerable<T>,其中包含來自兩個輸入序列的項目,但不包括重複的項目。An IEnumerable<T> that contains the elements from both input sequences, excluding duplicates.

例外狀況

firstsecondnullfirst or second is null.

範例

下列範例示範如何執行可用於方法的相等比較子 UnionThe following example shows how to implement an equality comparer that can be used in the Union method.

public class Product
{
    public string Name { get; set; }
    public int Code { get; set; }
}

// Custom comparer for the Product class
class ProductComparer : IEqualityComparer<Product>
{
    // Products are equal if their names and product numbers are equal.
    public bool Equals(Product x, Product y)
    {

        //Check whether the compared objects reference the same data.
        if (Object.ReferenceEquals(x, y)) return true;

        //Check whether any of the compared objects is null.
        if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
            return false;

        //Check whether the products' properties are equal.
        return x.Code == y.Code && x.Name == y.Name;
    }

    // If Equals() returns true for a pair of objects
    // then GetHashCode() must return the same value for these objects.

    public int GetHashCode(Product product)
    {
        //Check whether the object is null
        if (Object.ReferenceEquals(product, null)) return 0;

        //Get hash code for the Name field if it is not null.
        int hashProductName = product.Name == null ? 0 : product.Name.GetHashCode();

        //Get hash code for the Code field.
        int hashProductCode = product.Code.GetHashCode();

        //Calculate the hash code for the product.
        return hashProductName ^ hashProductCode;
    }
}
Public Class Product
    Public Property Name As String
    Public Property Code As Integer
End Class

' Custom comparer for the Product class
Public Class ProductComparer
    Implements IEqualityComparer(Of Product)

    Public Function Equals1(
        ByVal x As Product, 
        ByVal y As Product
        ) As Boolean Implements IEqualityComparer(Of Product).Equals

        ' Check whether the compared objects reference the same data.
        If x Is y Then Return True

        'Check whether any of the compared objects is null.
        If x Is Nothing OrElse y Is Nothing Then Return False

        ' Check whether the products' properties are equal.
        Return (x.Code = y.Code) AndAlso (x.Name = y.Name)
    End Function

    Public Function GetHashCode1(
        ByVal product As Product
        ) As Integer Implements IEqualityComparer(Of Product).GetHashCode

        ' Check whether the object is null.
        If product Is Nothing Then Return 0

        ' Get hash code for the Name field if it is not null.
        Dim hashProductName = 
            If(product.Name Is Nothing, 0, product.Name.GetHashCode())

        ' Get hash code for the Code field.
        Dim hashProductCode = product.Code.GetHashCode()

        ' Calculate the hash code for the product.
        Return hashProductName Xor hashProductCode
    End Function
End Class

在您執行此比較子之後,您可以 Product 在方法中使用物件的順序 Union ,如下列範例所示:After you implement this comparer, you can use sequences of Product objects in the Union method, as shown in the following example:

Product[] store1 = { new Product { Name = "apple", Code = 9 },
                       new Product { Name = "orange", Code = 4 } };

Product[] store2 = { new Product { Name = "apple", Code = 9 },
                       new Product { Name = "lemon", Code = 12 } };
Dim store1() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}}

Dim store2() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "lemon", .Code = 12}}
//Get the products from the both arrays
//excluding duplicates.

IEnumerable<Product> union =
  store1.Union(store2, new ProductComparer());

foreach (var product in union)
    Console.WriteLine(product.Name + " " + product.Code);

/*
    This code produces the following output:

    apple 9
    orange 4
    lemon 12
*/
' Get the products from the both arrays
' excluding duplicates.

Dim union = store1.Union(store2, New ProductComparer())

For Each product In union
    Console.WriteLine(product.Name & " " & product.Code)
Next

' This code produces the following output:
'
' apple 9
' orange 4
' lemon 12
' 

備註

這個方法是使用延後執行所執行。This method is implemented by using deferred execution. 立即傳回值是一個物件,它會儲存執行動作所需的所有資訊。The immediate return value is an object that stores all the information that is required to perform the action. 這個方法所表示的查詢不會執行,直到以 GetEnumerator foreach Visual c # 或 Visual Basic 中的方法來列舉物件為止 For EachThe 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.

如果 comparernull ,則會使用預設的相等比較子 Default 來比較值。If comparer is null, the default equality comparer, Default, is used to compare values.

列舉這個方法所傳回的物件時,會 Unionfirst second 該順序列舉和產生每個尚未產生的元素。When the object returned by this method is enumerated, Union enumerates first and second in that order and yields each element that has not already been yielded.

Concat方法與 Union 方法不同,因為方法會傳回 Concat 輸入序列中的所有元素(包括重複專案),而只會傳回 Union 唯一的值。The Concat method differs from the Union method because the Concat method returns all the elements in the input sequences including duplicates, whereas Union returns only unique values.

適用於

產品 推出的版本