Enumerable.SelectMany メソッド

定義

シーケンスの各要素を IEnumerable<T> に射影し、結果のシーケンスを 1 つのシーケンスに平坦化します。Projects each element of a sequence to an IEnumerable<T> and flattens the resulting sequences into one sequence.

オーバーロード

SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>)

シーケンスの各要素を IEnumerable<T> に射影し、結果のシーケンスを 1 つのシーケンスに平坦化して、その各要素に対して結果のセレクター関数を呼び出します。Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein.

SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>)

シーケンスの各要素を IEnumerable<T> に射影し、結果のシーケンスを 1 つのシーケンスに平坦化して、その各要素に対して結果のセレクター関数を呼び出します。Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. 各ソース要素のインデックスは、その要素の中間の射影されたフォームで使用されます。The index of each source element is used in the intermediate projected form of that element.

SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>)

シーケンスの各要素を IEnumerable<T> に射影し、結果のシーケンスを 1 つのシーケンスに平坦化します。Projects each element of a sequence to an IEnumerable<T> and flattens the resulting sequences into one sequence.

SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>)

シーケンスの各要素を IEnumerable<T> に射影し、結果のシーケンスを 1 つのシーケンスに平坦化します。Projects each element of a sequence to an IEnumerable<T>, and flattens the resulting sequences into one sequence. 各ソース要素のインデックスは、その要素の射影されたフォームで使用されます。The index of each source element is used in the projected form of that element.

SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>)

シーケンスの各要素を IEnumerable<T> に射影し、結果のシーケンスを 1 つのシーケンスに平坦化して、その各要素に対して結果のセレクター関数を呼び出します。Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein.

public:
generic <typename TSource, typename TCollection, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ SelectMany(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, System::Collections::Generic::IEnumerable<TCollection> ^> ^ collectionSelector, Func<TSource, TCollection, TResult> ^ resultSelector);
public static System.Collections.Generic.IEnumerable<TResult> SelectMany<TSource,TCollection,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,System.Collections.Generic.IEnumerable<TCollection>> collectionSelector, Func<TSource,TCollection,TResult> resultSelector);
static member SelectMany : seq<'Source> * Func<'Source, seq<'Collection>> * Func<'Source, 'Collection, 'Result> -> seq<'Result>
<Extension()>
Public Function SelectMany(Of TSource, TCollection, TResult) (source As IEnumerable(Of TSource), collectionSelector As Func(Of TSource, IEnumerable(Of TCollection)), resultSelector As Func(Of TSource, TCollection, TResult)) As IEnumerable(Of TResult)

型パラメーター

TSource

source の要素の型。The type of the elements of source.

TCollection

collectionSelector によって収集される中間要素の型。The type of the intermediate elements collected by collectionSelector.

TResult

結果のシーケンスの要素の型。The type of the elements of the resulting sequence.

パラメーター

source
IEnumerable<TSource>

射影する値のシーケンス。A sequence of values to project.

collectionSelector
Func<TSource,IEnumerable<TCollection>>

入力シーケンスの各要素に適用する変換関数。A transform function to apply to each element of the input sequence.

resultSelector
Func<TSource,TCollection,TResult>

中間シーケンスの各要素に適用する変換関数。A transform function to apply to each element of the intermediate sequence.

戻り値

IEnumerable<TResult>

collectionSelector の各要素で一対多の変換関数 source を呼び出し、こうしたシーケンスの各要素とそれに対応するソース要素を結果の要素に割り当てた結果として得られる要素を含む IEnumerable<T>An IEnumerable<T> whose elements are the result of invoking the one-to-many transform function collectionSelector on each element of source and then mapping each of those sequence elements and their corresponding source element to a result element.

例外

sourcecollectionSelector、または resultSelector は、null です。source or collectionSelector or resultSelector is null.

次のコード例では、SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>) を使用して、配列に対して一対多の射影を実行し、結果セレクター関数を使用して、@no__t への最後の呼び出しのために、ソースシーケンスの各対応する要素をスコープ内に保持する方法を示します。The following code example demonstrates how to use SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>) to perform a one-to-many projection over an array and use a result selector function to keep each corresponding element from the source sequence in scope for the final call to Select.

class PetOwner
{
    public string Name { get; set; }
    public List<string> Pets { get; set; }
}

public static void SelectManyEx3()
{
    PetOwner[] petOwners =
        { new PetOwner { Name="Higa", 
              Pets = new List<string>{ "Scruffy", "Sam" } },
          new PetOwner { Name="Ashkenazi", 
              Pets = new List<string>{ "Walker", "Sugar" } },
          new PetOwner { Name="Price", 
              Pets = new List<string>{ "Scratches", "Diesel" } },
          new PetOwner { Name="Hines", 
              Pets = new List<string>{ "Dusty" } } };

    // Project the pet owner's name and the pet's name.
    var query =
        petOwners
        .SelectMany(petOwner => petOwner.Pets, (petOwner, petName) => new { petOwner, petName })
        .Where(ownerAndPet => ownerAndPet.petName.StartsWith("S"))
        .Select(ownerAndPet =>
                new
                {
                    Owner = ownerAndPet.petOwner.Name,
                    Pet = ownerAndPet.petName
                }
        );

    // Print the results.
    foreach (var obj in query)
    {
        Console.WriteLine(obj);
    }
}

// This code produces the following output:
//
// {Owner=Higa, Pet=Scruffy}
// {Owner=Higa, Pet=Sam}
// {Owner=Ashkenazi, Pet=Sugar}
// {Owner=Price, Pet=Scratches}
Structure PetOwner
    Public Name As String
    Public Pets() As String
End Structure

Sub SelectManyEx3()
    ' Create an array of PetOwner objects.
    Dim petOwners() As PetOwner =
{New PetOwner With
 {.Name = "Higa", .Pets = New String() {"Scruffy", "Sam"}},
 New PetOwner With
 {.Name = "Ashkenazi", .Pets = New String() {"Walker", "Sugar"}},
 New PetOwner With
 {.Name = "Price", .Pets = New String() {"Scratches", "Diesel"}},
 New PetOwner With
 {.Name = "Hines", .Pets = New String() {"Dusty"}}}

    ' Project an anonymous type that consists of
    ' the owner's name and the pet's name (string).
    Dim query =
petOwners _
.SelectMany(
    Function(petOwner) petOwner.Pets,
    Function(petOwner, petName) New With {petOwner, petName}) _
.Where(Function(ownerAndPet) ownerAndPet.petName.StartsWith("S")) _
.Select(Function(ownerAndPet) _
       New With {.Owner = ownerAndPet.petOwner.Name,
                 .Pet = ownerAndPet.petName
       })

    Dim output As New System.Text.StringBuilder
    For Each obj In query
        output.AppendLine(String.Format("Owner={0}, Pet={1}", obj.Owner, obj.Pet))
    Next

    ' Display the output.
    MsgBox(output.ToString())
End Sub

' This code produces the following output:
'
' Owner=Higa, Pet=Scruffy
' Owner=Higa, Pet=Sam
' Owner=Ashkenazi, Pet=Sugar
' Owner=Price, Pet=Scratches

注釈

このメソッドは、遅延実行を使用して実装されます。This method is implemented by using deferred execution. イミディエイトの戻り値は、アクションを実行するために必要なすべての情報を格納するオブジェクトです。The immediate return value is an object that stores all the information that is required to perform the action. か、呼び出すことによって、オブジェクトが列挙されるまで、このメソッドによって表されるクエリは実行されません、GetEnumeratorメソッドを使用して直接またはforeachVisual C# またはFor EachVisual Basic で。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.

@No__t-0 メソッドは、SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>) の呼び出しの後に発生するクエリロジックのスコープで source の要素を保持する必要がある場合に便利です。The SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>) method is useful when you have to keep the elements of source in scope for query logic that occurs after the call to SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>). コード例については、「使用例」のセクションを参照してください。See the Example section for a code example. @No__t-0 型のオブジェクトと型が TCollection のオブジェクトの間に双方向のリレーションシップがある場合 (つまり、型 TCollection のオブジェクトが、そのオブジェクトを生成した @no__t 3 オブジェクトを取得するためのプロパティを提供している場合)、SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>) のこのオーバーロードは必要ありません。If there is a bidirectional relationship between objects of type TSource and objects of type TCollection, that is, if an object of type TCollection provides a property to retrieve the TSource object that produced it, you do not need this overload of SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>). 代わりに、SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>) を使用して、TCollection オブジェクトを介して TSource オブジェクトに戻ることができます。Instead, you can use SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>) and navigate back to the TSource object through the TCollection object.

クエリ式の構文で各from句 (Visual C#) またはFromの呼び出しに変換されるいずれかの句 (Visual Basic) の頭文字の後SelectManyします。In query expression syntax, each from clause (Visual C#) or From clause (Visual Basic) after the initial one translates to an invocation of SelectMany.

こちらもご覧ください

SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>)

シーケンスの各要素を IEnumerable<T> に射影し、結果のシーケンスを 1 つのシーケンスに平坦化して、その各要素に対して結果のセレクター関数を呼び出します。Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. 各ソース要素のインデックスは、その要素の中間の射影されたフォームで使用されます。The index of each source element is used in the intermediate projected form of that element.

public:
generic <typename TSource, typename TCollection, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ SelectMany(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, int, System::Collections::Generic::IEnumerable<TCollection> ^> ^ collectionSelector, Func<TSource, TCollection, TResult> ^ resultSelector);
public static System.Collections.Generic.IEnumerable<TResult> SelectMany<TSource,TCollection,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,int,System.Collections.Generic.IEnumerable<TCollection>> collectionSelector, Func<TSource,TCollection,TResult> resultSelector);
static member SelectMany : seq<'Source> * Func<'Source, int, seq<'Collection>> * Func<'Source, 'Collection, 'Result> -> seq<'Result>
<Extension()>
Public Function SelectMany(Of TSource, TCollection, TResult) (source As IEnumerable(Of TSource), collectionSelector As Func(Of TSource, Integer, IEnumerable(Of TCollection)), resultSelector As Func(Of TSource, TCollection, TResult)) As IEnumerable(Of TResult)

型パラメーター

TSource

source の要素の型。The type of the elements of source.

TCollection

collectionSelector によって収集される中間要素の型。The type of the intermediate elements collected by collectionSelector.

TResult

結果のシーケンスの要素の型。The type of the elements of the resulting sequence.

パラメーター

source
IEnumerable<TSource>

射影する値のシーケンス。A sequence of values to project.

collectionSelector
Func<TSource,Int32,IEnumerable<TCollection>>

各ソース要素に適用する変換関数。この関数の 2 つ目のパラメーターは、ソース要素のインデックスを表します。A transform function to apply to each source element; the second parameter of the function represents the index of the source element.

resultSelector
Func<TSource,TCollection,TResult>

中間シーケンスの各要素に適用する変換関数。A transform function to apply to each element of the intermediate sequence.

戻り値

IEnumerable<TResult>

collectionSelector の各要素で一対多の変換関数 source を呼び出し、こうしたシーケンスの各要素とそれに対応するソース要素を結果の要素に割り当てた結果として得られる要素を含む IEnumerable<T>An IEnumerable<T> whose elements are the result of invoking the one-to-many transform function collectionSelector on each element of source and then mapping each of those sequence elements and their corresponding source element to a result element.

例外

sourcecollectionSelector、または resultSelector は、null です。source or collectionSelector or resultSelector is null.

注釈

このメソッドは、遅延実行を使用して実装されます。This method is implemented by using deferred execution. イミディエイトの戻り値は、アクションを実行するために必要なすべての情報を格納するオブジェクトです。The immediate return value is an object that stores all the information that is required to perform the action. か、呼び出すことによって、オブジェクトが列挙されるまで、このメソッドによって表されるクエリは実行されません、GetEnumeratorメソッドを使用して直接またはforeachVisual C# またはFor EachVisual Basic で。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.

@No__t-0 メソッドは、SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>) の呼び出しの後に発生するクエリロジックのスコープで source の要素を保持する必要がある場合に便利です。The SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>) method is useful when you have to keep the elements of source in scope for query logic that occurs after the call to SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>). コード例については、「使用例」のセクションを参照してください。See the Example section for a code example. @No__t-0 型のオブジェクトと型が TCollection のオブジェクトの間に双方向のリレーションシップがある場合 (つまり、型 TCollection のオブジェクトが、そのオブジェクトを生成した @no__t 3 オブジェクトを取得するためのプロパティを提供している場合)、SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>) のこのオーバーロードは必要ありません。If there is a bidirectional relationship between objects of type TSource and objects of type TCollection, that is, if an object of type TCollection provides a property to retrieve the TSource object that produced it, you do not need this overload of SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>). 代わりに、SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>) を使用して、TCollection オブジェクトを介して TSource オブジェクトに戻ることができます。Instead, you can use SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>) and navigate back to the TSource object through the TCollection object.

SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>)

シーケンスの各要素を IEnumerable<T> に射影し、結果のシーケンスを 1 つのシーケンスに平坦化します。Projects each element of a sequence to an IEnumerable<T> and flattens the resulting sequences into one sequence.

public:
generic <typename TSource, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ SelectMany(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, System::Collections::Generic::IEnumerable<TResult> ^> ^ selector);
public static System.Collections.Generic.IEnumerable<TResult> SelectMany<TSource,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,System.Collections.Generic.IEnumerable<TResult>> selector);
static member SelectMany : seq<'Source> * Func<'Source, seq<'Result>> -> seq<'Result>
<Extension()>
Public Function SelectMany(Of TSource, TResult) (source As IEnumerable(Of TSource), selector As Func(Of TSource, IEnumerable(Of TResult))) As IEnumerable(Of TResult)

型パラメーター

TSource

source の要素の型。The type of the elements of source.

TResult

selector によって返されるシーケンスの要素の型。The type of the elements of the sequence returned by selector.

パラメーター

source
IEnumerable<TSource>

射影する値のシーケンス。A sequence of values to project.

selector
Func<TSource,IEnumerable<TResult>>

各要素に適用する変換関数。A transform function to apply to each element.

戻り値

IEnumerable<TResult>

入力シーケンスの各要素に対して一対多の変換関数を呼び出した結果として得られる要素を含む IEnumerable<T>An IEnumerable<T> whose elements are the result of invoking the one-to-many transform function on each element of the input sequence.

例外

source または selectornull です。source or selector is null.

次のコード例では、SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>) を使用して、配列に対して一対多の射影を実行する方法を示します。The following code example demonstrates how to use SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>) to perform a one-to-many projection over an array.

           class PetOwner
           {
               public string Name { get; set; }
               public List<String> Pets { get; set; }
           }

           public static void SelectManyEx1()
           {
               PetOwner[] petOwners = 
                   { new PetOwner { Name="Higa, Sidney", 
                         Pets = new List<string>{ "Scruffy", "Sam" } },
                     new PetOwner { Name="Ashkenazi, Ronen", 
                         Pets = new List<string>{ "Walker", "Sugar" } },
                     new PetOwner { Name="Price, Vernette", 
                         Pets = new List<string>{ "Scratches", "Diesel" } } };

               // Query using SelectMany().
               IEnumerable<string> query1 = petOwners.SelectMany(petOwner => petOwner.Pets);

               Console.WriteLine("Using SelectMany():");

               // Only one foreach loop is required to iterate 
               // through the results since it is a
               // one-dimensional collection.
               foreach (string pet in query1)
               {
                   Console.WriteLine(pet);
               }

               // This code shows how to use Select() 
               // instead of SelectMany().
               IEnumerable<List<String>> query2 =
                   petOwners.Select(petOwner => petOwner.Pets);

               Console.WriteLine("\nUsing Select():");

               // Notice that two foreach loops are required to 
               // iterate through the results
               // because the query returns a collection of arrays.
               foreach (List<String> petList in query2)
               {
                   foreach (string pet in petList)
                   {
                       Console.WriteLine(pet);
                   }
                   Console.WriteLine();
               }
           }

           /*
            This code produces the following output:
           
            Using SelectMany():
            Scruffy
            Sam
            Walker
            Sugar
            Scratches
            Diesel

            Using Select():
            Scruffy
            Sam

            Walker
            Sugar

            Scratches
            Diesel
           */
Structure PetOwner
    Public Name As String
    Public Pets() As String
End Structure

Sub SelectManyEx1()
    ' Create an array of PetOwner objects.
    Dim petOwners() As PetOwner =
{New PetOwner With
 {.Name = "Higa, Sidney", .Pets = New String() {"Scruffy", "Sam"}},
 New PetOwner With
 {.Name = "Ashkenazi, Ronen", .Pets = New String() {"Walker", "Sugar"}},
 New PetOwner With
 {.Name = "Price, Vernette", .Pets = New String() {"Scratches", "Diesel"}}}

    ' Call SelectMany() to gather all pets into a "flat" sequence.
    Dim query1 As IEnumerable(Of String) =
petOwners.SelectMany(Function(petOwner) petOwner.Pets)

    Dim output As New System.Text.StringBuilder("Using SelectMany():" & vbCrLf)
    ' Only one foreach loop is required to iterate through 
    ' the results because it is a one-dimensional collection.
    For Each pet As String In query1
        output.AppendLine(pet)
    Next

    ' This code demonstrates how to use Select() instead 
    ' of SelectMany() to get the same result.
    Dim query2 As IEnumerable(Of String()) =
petOwners.Select(Function(petOwner) petOwner.Pets)
    output.AppendLine(vbCrLf & "Using Select():")
    ' Notice that two foreach loops are required to iterate through 
    ' the results because the query returns a collection of arrays.
    For Each petArray() As String In query2
        For Each pet As String In petArray
            output.AppendLine(pet)
        Next
    Next

    ' Display the output.
    MsgBox(output.ToString())
End Sub

' This code produces the following output:
'
' Using SelectMany():
' Scruffy
' Sam
' Walker
' Sugar
' Scratches
' Diesel
'
' Using Select():
' Scruffy
' Sam
' Walker
' Sugar
' Scratches
' Diesel

注釈

このメソッドは、遅延実行を使用して実装されます。This method is implemented by using deferred execution. イミディエイトの戻り値は、アクションを実行するために必要なすべての情報を格納するオブジェクトです。The immediate return value is an object that stores all the information that is required to perform the action. か、呼び出すことによって、オブジェクトが列挙されるまで、このメソッドによって表されるクエリは実行されません、GetEnumeratorメソッドを使用して直接またはforeachVisual C# またはFor EachVisual Basic で。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.

@No__t-0 メソッドは、入力シーケンスを列挙し、変換関数を使用して各要素を IEnumerable<T> にマップしてから、各 IEnumerable<T> オブジェクトの要素を列挙して生成します。The SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>) method enumerates the input sequence, uses a transform function to map each element to an IEnumerable<T>, and then enumerates and yields the elements of each such IEnumerable<T> object. つまり、source の各要素に対して selector が呼び出され、一連の値が返されます。That is, for each element of source, selector is invoked and a sequence of values is returned. SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>) は、この2次元コレクションコレクションを1次元の @no__t に平坦化して返します。SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>) then flattens this two-dimensional collection of collections into a one-dimensional IEnumerable<T> and returns it. たとえば、クエリで SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>) を使用してデータベース内の各顧客の注文 (型 Order) を取得した場合、結果は Visual Basic の IEnumerable<Order> C#型または IEnumerable(Of Order) になります。For example, if a query uses SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>) to obtain the orders (of type Order) for each customer in a database, the result is of type IEnumerable<Order> in C# or IEnumerable(Of Order) in Visual Basic. クエリで Select を使用して注文を取得した場合、注文のコレクションのコレクションは結合されず、結果は Visual Basic 内のC# IEnumerable<List<Order>> または IEnumerable(Of List(Of Order)) の型になります。If instead the query uses Select to obtain the orders, the collection of collections of orders is not combined and the result is of type IEnumerable<List<Order>> in C# or IEnumerable(Of List(Of Order)) in Visual Basic.

クエリ式の構文で各from句 (Visual C#) またはFromの呼び出しに変換されるいずれかの句 (Visual Basic) の頭文字の後SelectManyします。In query expression syntax, each from clause (Visual C#) or From clause (Visual Basic) after the initial one translates to an invocation of SelectMany.

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SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>)

シーケンスの各要素を IEnumerable<T> に射影し、結果のシーケンスを 1 つのシーケンスに平坦化します。Projects each element of a sequence to an IEnumerable<T>, and flattens the resulting sequences into one sequence. 各ソース要素のインデックスは、その要素の射影されたフォームで使用されます。The index of each source element is used in the projected form of that element.

public:
generic <typename TSource, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ SelectMany(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, int, System::Collections::Generic::IEnumerable<TResult> ^> ^ selector);
public static System.Collections.Generic.IEnumerable<TResult> SelectMany<TSource,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,int,System.Collections.Generic.IEnumerable<TResult>> selector);
static member SelectMany : seq<'Source> * Func<'Source, int, seq<'Result>> -> seq<'Result>
<Extension()>
Public Function SelectMany(Of TSource, TResult) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Integer, IEnumerable(Of TResult))) As IEnumerable(Of TResult)

型パラメーター

TSource

source の要素の型。The type of the elements of source.

TResult

selector によって返されるシーケンスの要素の型。The type of the elements of the sequence returned by selector.

パラメーター

source
IEnumerable<TSource>

射影する値のシーケンス。A sequence of values to project.

selector
Func<TSource,Int32,IEnumerable<TResult>>

各ソース要素に適用する変換関数。この関数の 2 つ目のパラメーターは、ソース要素のインデックスを表します。A transform function to apply to each source element; the second parameter of the function represents the index of the source element.

戻り値

IEnumerable<TResult>

入力シーケンスの各要素に対して一対多の変換関数を呼び出した結果として得られる要素を含む IEnumerable<T>An IEnumerable<T> whose elements are the result of invoking the one-to-many transform function on each element of an input sequence.

例外

source または selectornull です。source or selector is null.

次のコード例では SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>) を使用して、配列に対して一対多の射影を実行し、各外側の要素のインデックスを使用する方法を示します。The following code example demonstrates how to use SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>) to perform a one-to-many projection over an array and use the index of each outer element.

class PetOwner
{
    public string Name { get; set; }
    public List<string> Pets { get; set; }
}

public static void SelectManyEx2()
{
    PetOwner[] petOwners = 
        { new PetOwner { Name="Higa, Sidney", 
              Pets = new List<string>{ "Scruffy", "Sam" } },
          new PetOwner { Name="Ashkenazi, Ronen", 
              Pets = new List<string>{ "Walker", "Sugar" } },
          new PetOwner { Name="Price, Vernette", 
              Pets = new List<string>{ "Scratches", "Diesel" } },
          new PetOwner { Name="Hines, Patrick", 
              Pets = new List<string>{ "Dusty" } } };

    // Project the items in the array by appending the index 
    // of each PetOwner to each pet's name in that petOwner's 
    // array of pets.
    IEnumerable<string> query =
        petOwners.SelectMany((petOwner, index) =>
                                 petOwner.Pets.Select(pet => index + pet));

    foreach (string pet in query)
    {
        Console.WriteLine(pet);
    }
}

// This code produces the following output:
//
// 0Scruffy
// 0Sam
// 1Walker
// 1Sugar
// 2Scratches
// 2Diesel
// 3Dusty
Structure PetOwner
    Public Name As String
    Public Pets() As String
End Structure

Sub SelectManyEx2()
    ' Create an array of PetOwner objects.
    Dim petOwners() As PetOwner =
{New PetOwner With
 {.Name = "Higa, Sidney", .Pets = New String() {"Scruffy", "Sam"}},
 New PetOwner With
 {.Name = "Ashkenazi, Ronen", .Pets = New String() {"Walker", "Sugar"}},
 New PetOwner With
 {.Name = "Price, Vernette", .Pets = New String() {"Scratches", "Diesel"}},
 New PetOwner With
 {.Name = "Hines, Patrick", .Pets = New String() {"Dusty"}}}

    ' Project the items in the array by appending the index 
    ' of each PetOwner to each pet's name in that petOwner's 
    ' array of pets.
    Dim query As IEnumerable(Of String) =
petOwners.SelectMany(Function(petOwner, index) _
                         petOwner.Pets.Select(Function(pet) _
                                                  index.ToString() + pet))

    Dim output As New System.Text.StringBuilder
    For Each pet As String In query
        output.AppendLine(pet)
    Next

    ' Display the output.
    MsgBox(output.ToString())
End Sub

注釈

このメソッドは、遅延実行を使用して実装されます。This method is implemented by using deferred execution. イミディエイトの戻り値は、アクションを実行するために必要なすべての情報を格納するオブジェクトです。The immediate return value is an object that stores all the information that is required to perform the action. か、呼び出すことによって、オブジェクトが列挙されるまで、このメソッドによって表されるクエリは実行されません、GetEnumeratorメソッドを使用して直接またはforeachVisual C# またはFor EachVisual Basic で。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.

@No__t-0 メソッドは、入力シーケンスを列挙し、変換関数を使用して各要素を IEnumerable<T> にマップしてから、各 IEnumerable<T> オブジェクトの要素を列挙して生成します。The SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>) method enumerates the input sequence, uses a transform function to map each element to an IEnumerable<T>, and then enumerates and yields the elements of each such IEnumerable<T> object. つまり、source の各要素に対して selector が呼び出され、一連の値が返されます。That is, for each element of source, selector is invoked and a sequence of values is returned. SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>) は、この2次元コレクションコレクションを1次元の @no__t に平坦化して返します。SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>) then flattens this two-dimensional collection of collections into a one-dimensional IEnumerable<T> and returns it. たとえば、クエリで SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>) を使用してデータベース内の各顧客の注文 (型 Order) を取得した場合、結果は Visual Basic の IEnumerable<Order> C#型または IEnumerable(Of Order) になります。For example, if a query uses SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>) to obtain the orders (of type Order) for each customer in a database, the result is of type IEnumerable<Order> in C# or IEnumerable(Of Order) in Visual Basic. クエリで Select を使用して注文を取得した場合、注文のコレクションのコレクションは結合されず、結果は Visual Basic 内のC# IEnumerable<List<Order>> または IEnumerable(Of List(Of Order)) の型になります。If instead the query uses Select to obtain the orders, the collection of collections of orders is not combined and the result is of type IEnumerable<List<Order>> in C# or IEnumerable(Of List(Of Order)) in Visual Basic.

@No__t-0 の最初の引数は、処理する要素を表します。The first argument to selector represents the element to process. @No__t-0 の2番目の引数は、ソースシーケンス内のその要素の0から始まるインデックスを表します。The second argument to selector represents the zero-based index of that element in the source sequence. これは、要素が既知の順序であり、特定のインデックスにある要素を使用して何らかの処理を行う場合に便利です。たとえば、のようになります。This can be useful if the elements are in a known order and you want to do something with an element at a particular index, for example. また、1つまたは複数の要素のインデックスを取得する場合にも役立ちます。It can also be useful if you want to retrieve the index of one or more elements.

適用対象