Enumerable.GroupBy Metoda

public:
generic <typename TSource, typename TKey, typename TElement, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ GroupBy(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, Func<TSource, TElement> ^ elementSelector, Func<TKey, System::Collections::Generic::IEnumerable<TElement> ^, TResult> ^ resultSelector);

public static System.Collections.Generic.IEnumerable<TResult> GroupBy<TSource,TKey,TElement,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TSource,TElement> elementSelector, Func<TKey,System.Collections.Generic.IEnumerable<TElement>,TResult> resultSelector);

static member GroupBy : seq<'Source> * Func<'Source, 'Key> * Func<'Source, 'Element> * Func<'Key, seq<'Element>, 'Result> -> seq<'Result>

<Extension()>
Public Function GroupBy(Of TSource, TKey, TElement, TResult) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), elementSelector As Func(Of TSource, TElement), resultSelector As Func(Of TKey, IEnumerable(Of TElement), TResult)) As IEnumerable(Of TResult)

Parametry typu

Parametry

Zwraca

IEnumerable<TResult>

Kolekcja elementów typu, TResult gdzie każdy element reprezentuje projekcję nad grupą i jej klucz.A collection of elements of type TResult where each element represents a projection over a group and its key.

Przykłady

Poniższy przykład kodu ilustruje sposób używania GroupBy<TSource,TKey,TElement,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, Func<TKey,IEnumerable<TElement>,TResult>) do grupowania rzutowanych elementów sekwencji, a następnie tworzenia kolejności wyników typu TResult .The following code example demonstrates how to use GroupBy<TSource,TKey,TElement,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, Func<TKey,IEnumerable<TElement>,TResult>) to group the projected elements of a sequence and then project a sequence of results of type TResult.

class Pet
{
    public string Name { get; set; }
    public double Age { get; set; }
}

public static void GroupByEx4()
{
    // Create a list of pets.
    List<Pet> petsList =
        new List<Pet>{ new Pet { Name="Barley", Age=8.3 },
                       new Pet { Name="Boots", Age=4.9 },
                       new Pet { Name="Whiskers", Age=1.5 },
                       new Pet { Name="Daisy", Age=4.3 } };

    // Group Pet.Age values by the Math.Floor of the age.
    // Then project an anonymous type from each group
    // that consists of the key, the count of the group's
    // elements, and the minimum and maximum age in the group.
    var query = petsList.GroupBy(
        pet => Math.Floor(pet.Age),
        pet => pet.Age,
        (baseAge, ages) => new
        {
            Key = baseAge,
            Count = ages.Count(),
            Min = ages.Min(),
            Max = ages.Max()
        });

    // Iterate over each anonymous type.
    foreach (var result in query)
    {
        Console.WriteLine("\nAge group: " + result.Key);
        Console.WriteLine("Number of pets in this age group: " + result.Count);
        Console.WriteLine("Minimum age: " + result.Min);
        Console.WriteLine("Maximum age: " + result.Max);
    }

    /*  This code produces the following output:

        Age group: 8
        Number of pets in this age group: 1
        Minimum age: 8.3
        Maximum age: 8.3

        Age group: 4
        Number of pets in this age group: 2
        Minimum age: 4.3
        Maximum age: 4.9

        Age group: 1
        Number of pets in this age group: 1
        Minimum age: 1.5
        Maximum age: 1.5
    */
}

Structure Pet
    Public Name As String
    Public Age As Double
End Structure

Public Sub GroupByEx4()
    ' Create a list of pets.
    Dim petsList As New List(Of Pet)(New Pet() _
                         {New Pet With {.Name = "Barley", .Age = 8.3},
                          New Pet With {.Name = "Boots", .Age = 4.9},
                          New Pet With {.Name = "Whiskers", .Age = 1.5},
                          New Pet With {.Name = "Daisy", .Age = 4.3}})

    ' Group Pet.Age values by the Math.Floor of the age.
    ' Then project an anonymous type from each group
    ' that consists of the key, the count of the group's
    ' elements, and the minimum and maximum age in the group.
    Dim query = petsList.GroupBy(
Function(pet) Math.Floor(pet.Age),
Function(pet) pet.Age,
Function(baseAge, ages) New With
    {.Key = baseAge,
    .Count = ages.Count(),
    .Min = ages.Min(),
    .Max = ages.Max()}
)

    Dim output As New System.Text.StringBuilder
    ' Iterate over each anonymous type.
    For Each result In query
        output.AppendLine(vbCrLf & "Age group: " & result.Key)
        output.AppendLine("Number of pets in this age group: " & result.Count)
        output.AppendLine("Minimum age: " & result.Min)
        output.AppendLine("Maximum age: " & result.Max)
    Next

    ' Display the output.
    Console.WriteLine(output.ToString)
End Sub

' This code produces the following output:

' Age group: 8
' Number of pets in this age group: 1
' Minimum age: 8.3
' Maximum age: 8.3
'
' Age group: 4
' Number of pets in this age group: 2
' Minimum age: 4.3
' Maximum age: 4.9
'
' Age group: 1
' Number of pets in this age group: 1
' Minimum age: 1.5
' Maximum age: 1.5

Uwagi

W składni wyrażenia zapytania, group by klauzula (Visual C#) lub Group By Into (Visual Basic) tłumaczy na wywołanie GroupBy .In query expression syntax, a group by (Visual C#) or Group By Into (Visual Basic) clause translates to an invocation of GroupBy.

public:
generic <typename TSource, typename TKey, typename TElement, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ GroupBy(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, Func<TSource, TElement> ^ elementSelector, Func<TKey, System::Collections::Generic::IEnumerable<TElement> ^, TResult> ^ resultSelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);

public static System.Collections.Generic.IEnumerable<TResult> GroupBy<TSource,TKey,TElement,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TSource,TElement> elementSelector, Func<TKey,System.Collections.Generic.IEnumerable<TElement>,TResult> resultSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);

public static System.Collections.Generic.IEnumerable<TResult> GroupBy<TSource,TKey,TElement,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TSource,TElement> elementSelector, Func<TKey,System.Collections.Generic.IEnumerable<TElement>,TResult> resultSelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer);

static member GroupBy : seq<'Source> * Func<'Source, 'Key> * Func<'Source, 'Element> * Func<'Key, seq<'Element>, 'Result> * System.Collections.Generic.IEqualityComparer<'Key> -> seq<'Result>

<Extension()>
Public Function GroupBy(Of TSource, TKey, TElement, TResult) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), elementSelector As Func(Of TSource, TElement), resultSelector As Func(Of TKey, IEnumerable(Of TElement), TResult), comparer As IEqualityComparer(Of TKey)) As IEnumerable(Of TResult)

Parametry typu

Parametry

Zwraca

IEnumerable<TResult>

Kolekcja elementów typu, TResult gdzie każdy element reprezentuje projekcję nad grupą i jej klucz.A collection of elements of type TResult where each element represents a projection over a group and its key.

public:
generic <typename TSource, typename TKey, typename TElement>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<System::Linq::IGrouping<TKey, TElement> ^> ^ GroupBy(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, Func<TSource, TElement> ^ elementSelector);

public static System.Collections.Generic.IEnumerable<System.Linq.IGrouping<TKey,TElement>> GroupBy<TSource,TKey,TElement> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TSource,TElement> elementSelector);

static member GroupBy : seq<'Source> * Func<'Source, 'Key> * Func<'Source, 'Element> -> seq<System.Linq.IGrouping<'Key, 'Element>>

<Extension()>
Public Function GroupBy(Of TSource, TKey, TElement) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), elementSelector As Func(Of TSource, TElement)) As IEnumerable(Of IGrouping(Of TKey, TElement))

Parametry typu

Parametry

Zwraca

IEnumerable<IGrouping<TKey,TElement>>

Interfejs IEnumerable < IGrouping < > > TKey, tele w języku C# lub IEnumerable (of IGrouping (of TKey, tele)) w Visual Basic, gdzie każdy IGrouping<TKey,TElement> obiekt zawiera kolekcję obiektów typu TElement i klucza.An IEnumerable<IGrouping<TKey, TElement>> in C# or IEnumerable(Of IGrouping(Of TKey, TElement)) in Visual Basic where each IGrouping<TKey,TElement> object contains a collection of objects of type TElement and a key.

Wyjątki

Przykłady

Poniższy przykład kodu pokazuje, jak używać GroupBy<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) do grupowania elementów sekwencji.The following code example demonstrates how to use GroupBy<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) to group the elements of a sequence.

class Pet
{
    public string Name { get; set; }
    public int Age { get; set; }
}

// Uses method-based query syntax.
public static void GroupByEx1()
{
    // Create a list of pets.
    List<Pet> pets =
        new List<Pet>{ new Pet { Name="Barley", Age=8 },
                       new Pet { Name="Boots", Age=4 },
                       new Pet { Name="Whiskers", Age=1 },
                       new Pet { Name="Daisy", Age=4 } };

    // Group the pets using Age as the key value
    // and selecting only the pet's Name for each value.
    IEnumerable<IGrouping<int, string>> query =
        pets.GroupBy(pet => pet.Age, pet => pet.Name);

    // Iterate over each IGrouping in the collection.
    foreach (IGrouping<int, string> petGroup in query)
    {
        // Print the key value of the IGrouping.
        Console.WriteLine(petGroup.Key);
        // Iterate over each value in the
        // IGrouping and print the value.
        foreach (string name in petGroup)
            Console.WriteLine("  {0}", name);
    }
}

/*
 This code produces the following output:

 8
   Barley
 4
   Boots
   Daisy
 1
   Whiskers
*/

Structure Pet
    Public Name As String
    Public Age As Integer
End Structure

Sub GroupByEx1()
    'Create a list of Pet objects.
    Dim pets As New List(Of Pet)(New Pet() _
                         {New Pet With {.Name = "Barley", .Age = 8},
                          New Pet With {.Name = "Boots", .Age = 4},
                          New Pet With {.Name = "Whiskers", .Age = 1},
                          New Pet With {.Name = "Daisy", .Age = 4}})

    ' Group the pets using Age as the key 
    ' and selecting only the pet's Name for each value.
    Dim query As IEnumerable(Of IGrouping(Of Integer, String)) =
pets.GroupBy(Function(pet) pet.Age,
             Function(pet) pet.Name)

    Dim output As New System.Text.StringBuilder
    ' Iterate over each IGrouping in the collection.
    For Each petGroup As IGrouping(Of Integer, String) In query
        ' Print the key value of the IGrouping.
        output.AppendLine(petGroup.Key)
        ' Iterate over each value in the IGrouping and print the value.
        For Each name As String In petGroup
            output.AppendLine("  " & name)
        Next
    Next

    ' Display the output.
    Console.WriteLine(output.ToString)
End Sub

' This code produces the following output:
'
' 8
'   Barley
' 4
'   Boots
'   Daisy
' 1
'   Whiskers

W składni wyrażenia zapytania, group by klauzula (Visual C#) lub Group By Into (Visual Basic) tłumaczy na wywołanie GroupBy .In query expression syntax, a group by (Visual C#) or Group By Into (Visual Basic) clause translates to an invocation of GroupBy. Tłumaczenie wyrażenia zapytania w poniższym przykładzie jest równoznaczne z kwerendą w powyższym przykładzie.The translation of the query expression in the following example is equivalent to the query in the example above.

IEnumerable<IGrouping<int, string>> query =
    from pet in pets
    group pet.Name by pet.Age;

    Dim query =
From pet In pets
Group pet.Name By Age = pet.Age Into ageGroup = Group

Uwagi

Ta metoda jest implementowana za pomocą odroczonego wykonania.This method is implemented by using deferred execution. Bezpośrednio zwracana wartość jest obiektem, który przechowuje wszystkie informacje wymagane do wykonania akcji.The immediate return value is an object that stores all the information that is required to perform the action. Zapytanie reprezentowane przez tę metodę nie jest wykonywane do momentu wyliczenia obiektu przez wywołanie jego GetEnumerator metody bezpośrednio lub przy użyciu foreach w Visual C# lub For Each w Visual Basic.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.

GroupBy<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>)Metoda zwraca kolekcję IGrouping<TKey,TElement> obiektów, jeden dla każdego napotkanego oddzielnego klucza.The GroupBy<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) method returns a collection of IGrouping<TKey,TElement> objects, one for each distinct key that was encountered. IGrouping<TKey,TElement>Jest to IEnumerable<T> również klucz skojarzony z jego elementami.An IGrouping<TKey,TElement> is an IEnumerable<T> that also has a key associated with its elements.

IGrouping<TKey,TElement>Obiekty są uzyskiwane w kolejności na podstawie kolejności elementów w programie source , która wygenerowała pierwszy klucz każdego z nich IGrouping<TKey,TElement> .The IGrouping<TKey,TElement> objects are yielded in an order based on the order of the elements in source that produced the first key of each IGrouping<TKey,TElement>. Elementy w grupowaniu są generowane w kolejności, w jakiej są wyświetlane elementy, w których zostały utworzone source .Elements in a grouping are yielded in the order that the elements that produced them appear in source.

Domyślna funkcja porównująca równość Default jest używana do porównywania kluczy.The default equality comparer Default is used to compare keys.

public:
generic <typename TSource, typename TKey, typename TElement>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<System::Linq::IGrouping<TKey, TElement> ^> ^ GroupBy(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, Func<TSource, TElement> ^ elementSelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);

public static System.Collections.Generic.IEnumerable<System.Linq.IGrouping<TKey,TElement>> GroupBy<TSource,TKey,TElement> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TSource,TElement> elementSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);

public static System.Collections.Generic.IEnumerable<System.Linq.IGrouping<TKey,TElement>> GroupBy<TSource,TKey,TElement> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TSource,TElement> elementSelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer);

static member GroupBy : seq<'Source> * Func<'Source, 'Key> * Func<'Source, 'Element> * System.Collections.Generic.IEqualityComparer<'Key> -> seq<System.Linq.IGrouping<'Key, 'Element>>

<Extension()>
Public Function GroupBy(Of TSource, TKey, TElement) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), elementSelector As Func(Of TSource, TElement), comparer As IEqualityComparer(Of TKey)) As IEnumerable(Of IGrouping(Of TKey, TElement))

Parametry typu

Parametry

Zwraca

IEnumerable<IGrouping<TKey,TElement>>

Interfejs IEnumerable < IGrouping < > > TKey, tele w języku C# lub IEnumerable (of IGrouping (of TKey, tele)) w Visual Basic, gdzie każdy IGrouping<TKey,TElement> obiekt zawiera kolekcję obiektów typu TElement i klucza.An IEnumerable<IGrouping<TKey, TElement>> in C# or IEnumerable(Of IGrouping(Of TKey, TElement)) in Visual Basic where each IGrouping<TKey,TElement> object contains a collection of objects of type TElement and a key.

Wyjątki

Uwagi

Ta metoda jest implementowana za pomocą odroczonego wykonania.This method is implemented by using deferred execution. Bezpośrednio zwracana wartość jest obiektem, który przechowuje wszystkie informacje wymagane do wykonania akcji.The immediate return value is an object that stores all the information that is required to perform the action. Zapytanie reprezentowane przez tę metodę nie jest wykonywane do momentu wyliczenia obiektu przez wywołanie jego GetEnumerator metody bezpośrednio lub przy użyciu foreach w Visual C# lub For Each w Visual Basic.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.

GroupBy<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>)Metoda zwraca kolekcję IGrouping<TKey,TElement> obiektów, jeden dla każdego napotkanego oddzielnego klucza.The GroupBy<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>) method returns a collection of IGrouping<TKey,TElement> objects, one for each distinct key that was encountered. IGrouping<TKey,TElement>Jest to IEnumerable<T> również klucz skojarzony z jego elementami.An IGrouping<TKey,TElement> is an IEnumerable<T> that also has a key associated with its elements.

IGrouping<TKey,TElement>Obiekty są uzyskiwane w kolejności na podstawie kolejności elementów w programie source , która wygenerowała pierwszy klucz każdego z nich IGrouping<TKey,TElement> .The IGrouping<TKey,TElement> objects are yielded in an order based on the order of the elements in source that produced the first key of each IGrouping<TKey,TElement>. Elementy w grupowaniu są generowane w kolejności, w jakiej są wyświetlane elementy, w których zostały utworzone source .Elements in a grouping are yielded in the order that the elements that produced them appear in source.

Jeśli comparer jest null , domyślną funkcję porównującą równość Default używa się do porównywania kluczy.If comparer is null, the default equality comparer Default is used to compare keys.

Jeśli dwa klucze są uważane za równe comparer , pierwszy klucz jest wybierany jako klucz dla tego grupowania.If two keys are considered equal according to comparer, the first key is chosen as the key for that grouping.

W składni wyrażenia zapytania, group by klauzula (Visual C#) lub Group By Into (Visual Basic) tłumaczy na wywołanie GroupBy .In query expression syntax, a group by (Visual C#) or Group By Into (Visual Basic) clause translates to an invocation of GroupBy. Aby uzyskać więcej informacji i przykłady użycia, zobacz klauzula Group i klauzula GROUP by.For more information and usage examples, see group clause and Group By Clause.

public:
generic <typename TSource, typename TKey, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ GroupBy(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, Func<TKey, System::Collections::Generic::IEnumerable<TSource> ^, TResult> ^ resultSelector);

public static System.Collections.Generic.IEnumerable<TResult> GroupBy<TSource,TKey,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TKey,System.Collections.Generic.IEnumerable<TSource>,TResult> resultSelector);

static member GroupBy : seq<'Source> * Func<'Source, 'Key> * Func<'Key, seq<'Source>, 'Result> -> seq<'Result>

<Extension()>
Public Function GroupBy(Of TSource, TKey, TResult) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), resultSelector As Func(Of TKey, IEnumerable(Of TSource), TResult)) As IEnumerable(Of TResult)

Parametry typu

Parametry

Zwraca

IEnumerable<TResult>

Kolekcja elementów typu, TResult gdzie każdy element reprezentuje projekcję nad grupą i jej klucz.A collection of elements of type TResult where each element represents a projection over a group and its key.

Przykłady

Poniższy przykład kodu demonstruje, jak używać GroupBy<TSource,TKey,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TKey,IEnumerable<TSource>,TResult>) do grupowania elementów sekwencji i projektu sekwencji wyników typu TResult .The following code example demonstrates how to use GroupBy<TSource,TKey,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TKey,IEnumerable<TSource>,TResult>) to group the elements of a sequence and project a sequence of results of type TResult.

class Pet
{
    public string Name { get; set; }
    public double Age { get; set; }
}

public static void GroupByEx3()
{
    // Create a list of pets.
    List<Pet> petsList =
        new List<Pet>{ new Pet { Name="Barley", Age=8.3 },
                       new Pet { Name="Boots", Age=4.9 },
                       new Pet { Name="Whiskers", Age=1.5 },
                       new Pet { Name="Daisy", Age=4.3 } };

    // Group Pet objects by the Math.Floor of their age.
    // Then project an anonymous type from each group
    // that consists of the key, the count of the group's
    // elements, and the minimum and maximum age in the group.
    var query = petsList.GroupBy(
        pet => Math.Floor(pet.Age),
        (age, pets) => new
        {
            Key = age,
            Count = pets.Count(),
            Min = pets.Min(pet => pet.Age),
            Max = pets.Max(pet => pet.Age)
        });

    // Iterate over each anonymous type.
    foreach (var result in query)
    {
        Console.WriteLine("\nAge group: " + result.Key);
        Console.WriteLine("Number of pets in this age group: " + result.Count);
        Console.WriteLine("Minimum age: " + result.Min);
        Console.WriteLine("Maximum age: " + result.Max);
    }

    /*  This code produces the following output:

        Age group: 8
        Number of pets in this age group: 1
        Minimum age: 8.3
        Maximum age: 8.3

        Age group: 4
        Number of pets in this age group: 2
        Minimum age: 4.3
        Maximum age: 4.9

        Age group: 1
        Number of pets in this age group: 1
        Minimum age: 1.5
        Maximum age: 1.5
    */
}

Structure Pet
    Public Name As String
    Public Age As Double
End Structure

Public Sub GroupByEx3()
    ' Create a list of pets.
    Dim petsList As New List(Of Pet)(New Pet() _
                         {New Pet With {.Name = "Barley", .Age = 8.3},
                          New Pet With {.Name = "Boots", .Age = 4.9},
                          New Pet With {.Name = "Whiskers", .Age = 1.5},
                          New Pet With {.Name = "Daisy", .Age = 4.3}})

    ' Group Pet objects by the Math.Floor of their age.
    ' Then project an anonymous type from each group
    ' that consists of the key, the count of the group's
    ' elements, and the minimum and maximum age in the group.
    Dim query = petsList.GroupBy(
Function(pet) Math.Floor(pet.Age),
Function(age, pets) New With
    {.Key = age,
    .Count = pets.Count(),
    .Min = pets.Min(Function(pet) pet.Age),
    .Max = pets.Max(Function(Pet) Pet.Age)}
)

    Dim output As New System.Text.StringBuilder
    ' Iterate over each anonymous type.
    For Each result In query
        output.AppendLine(vbCrLf & "Age group: " & result.Key)
        output.AppendLine("Number of pets in this age group: " & result.Count)
        output.AppendLine("Minimum age: " & result.Min)
        output.AppendLine("Maximum age: " & result.Max)
    Next

    ' Display the output.
    Console.WriteLine(output.ToString)
End Sub

' This code produces the following output:

' Age group: 8
' Number of pets in this age group: 1
' Minimum age: 8.3
' Maximum age: 8.3
'
' Age group: 4
' Number of pets in this age group: 2
' Minimum age: 4.3
' Maximum age: 4.9
'
' Age group: 1
' Number of pets in this age group: 1
' Minimum age: 1.5
' Maximum age: 1.5

Uwagi

W składni wyrażenia zapytania, group by klauzula (Visual C#) lub Group By Into (Visual Basic) tłumaczy na wywołanie GroupBy .In query expression syntax, a group by (Visual C#) or Group By Into (Visual Basic) clause translates to an invocation of GroupBy.

public:
generic <typename TSource, typename TKey, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ GroupBy(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, Func<TKey, System::Collections::Generic::IEnumerable<TSource> ^, TResult> ^ resultSelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);

public static System.Collections.Generic.IEnumerable<TResult> GroupBy<TSource,TKey,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TKey,System.Collections.Generic.IEnumerable<TSource>,TResult> resultSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);

public static System.Collections.Generic.IEnumerable<TResult> GroupBy<TSource,TKey,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TKey,System.Collections.Generic.IEnumerable<TSource>,TResult> resultSelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer);

static member GroupBy : seq<'Source> * Func<'Source, 'Key> * Func<'Key, seq<'Source>, 'Result> * System.Collections.Generic.IEqualityComparer<'Key> -> seq<'Result>

<Extension()>
Public Function GroupBy(Of TSource, TKey, TResult) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), resultSelector As Func(Of TKey, IEnumerable(Of TSource), TResult), comparer As IEqualityComparer(Of TKey)) As IEnumerable(Of TResult)

Parametry typu

Parametry

Zwraca

IEnumerable<TResult>

Kolekcja elementów typu, TResult gdzie każdy element reprezentuje projekcję nad grupą i jej klucz.A collection of elements of type TResult where each element represents a projection over a group and its key.

public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<System::Linq::IGrouping<TKey, TSource> ^> ^ GroupBy(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector);

public static System.Collections.Generic.IEnumerable<System.Linq.IGrouping<TKey,TSource>> GroupBy<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector);

static member GroupBy : seq<'Source> * Func<'Source, 'Key> -> seq<System.Linq.IGrouping<'Key, 'Source>>

<Extension()>
Public Function GroupBy(Of TSource, TKey) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey)) As IEnumerable(Of IGrouping(Of TKey, TSource))

Parametry typu

Parametry

Zwraca

IEnumerable<IGrouping<TKey,TSource>>

Interfejs IEnumerable < IGrouping < TKey, TSource > > w języku C# lub IEnumerable (of IGrouping (TKey, TSource)) w Visual Basic gdzie każdy IGrouping<TKey,TElement> obiekt zawiera sekwencję obiektów i klucz.An IEnumerable<IGrouping<TKey, TSource>> in C# or IEnumerable(Of IGrouping(Of TKey, TSource)) in Visual Basic where each IGrouping<TKey,TElement> object contains a sequence of objects and a key.

Wyjątki

Uwagi

Ta metoda jest implementowana za pomocą odroczonego wykonania.This method is implemented by using deferred execution. Bezpośrednio zwracana wartość jest obiektem, który przechowuje wszystkie informacje wymagane do wykonania akcji.The immediate return value is an object that stores all the information that is required to perform the action. Zapytanie reprezentowane przez tę metodę nie jest wykonywane do momentu wyliczenia obiektu przez wywołanie jego GetEnumerator metody bezpośrednio lub przy użyciu foreach w Visual C# lub For Each w Visual Basic.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.

GroupBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)Metoda zwraca kolekcję IGrouping<TKey,TElement> obiektów, jeden dla każdego napotkanego oddzielnego klucza.The GroupBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) method returns a collection of IGrouping<TKey,TElement> objects, one for each distinct key that was encountered. IGrouping<TKey,TElement>Jest to IEnumerable<T> również klucz skojarzony z jego elementami.An IGrouping<TKey,TElement> is an IEnumerable<T> that also has a key associated with its elements.

IGrouping<TKey,TElement>Obiekty są uzyskiwane w kolejności na podstawie kolejności elementów w programie source , która wygenerowała pierwszy klucz każdego z nich IGrouping<TKey,TElement> .The IGrouping<TKey,TElement> objects are yielded in an order based on the order of the elements in source that produced the first key of each IGrouping<TKey,TElement>. Elementy w grupowaniu są realizowane w kolejności, w której się znajdują source .Elements in a grouping are yielded in the order they appear in source.

Domyślna funkcja porównująca równość Default jest używana do porównywania kluczy.The default equality comparer Default is used to compare keys.

W składni wyrażenia zapytania, group by klauzula (Visual C#) lub Group By Into (Visual Basic) tłumaczy na wywołanie GroupBy .In query expression syntax, a group by (Visual C#) or Group By Into (Visual Basic) clause translates to an invocation of GroupBy. Aby uzyskać więcej informacji i przykłady użycia, zobacz klauzula Group i klauzula GROUP by.For more information and usage examples, see group clause and Group By Clause.

public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<System::Linq::IGrouping<TKey, TSource> ^> ^ GroupBy(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);

public static System.Collections.Generic.IEnumerable<System.Linq.IGrouping<TKey,TSource>> GroupBy<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);

public static System.Collections.Generic.IEnumerable<System.Linq.IGrouping<TKey,TSource>> GroupBy<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer);

static member GroupBy : seq<'Source> * Func<'Source, 'Key> * System.Collections.Generic.IEqualityComparer<'Key> -> seq<System.Linq.IGrouping<'Key, 'Source>>

<Extension()>
Public Function GroupBy(Of TSource, TKey) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), comparer As IEqualityComparer(Of TKey)) As IEnumerable(Of IGrouping(Of TKey, TSource))

Parametry typu

Parametry

Zwraca

IEnumerable<IGrouping<TKey,TSource>>

Interfejs IEnumerable < IGrouping < TKey, TSource > > w języku C# lub IEnumerable (of IGrouping (TKey, TSource)) w Visual Basic gdzie każdy IGrouping<TKey,TElement> obiekt zawiera kolekcję obiektów i klucz.An IEnumerable<IGrouping<TKey, TSource>> in C# or IEnumerable(Of IGrouping(Of TKey, TSource)) in Visual Basic where each IGrouping<TKey,TElement> object contains a collection of objects and a key.

Wyjątki

Uwagi

Ta metoda jest implementowana za pomocą odroczonego wykonania.This method is implemented by using deferred execution. Bezpośrednio zwracana wartość jest obiektem, który przechowuje wszystkie informacje wymagane do wykonania akcji.The immediate return value is an object that stores all the information that is required to perform the action. Zapytanie reprezentowane przez tę metodę nie jest wykonywane do momentu wyliczenia obiektu przez wywołanie jego GetEnumerator metody bezpośrednio lub przy użyciu foreach w Visual C# lub For Each w Visual Basic.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.

GroupBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>)Metoda zwraca kolekcję IGrouping<TKey,TElement> obiektów, jeden dla każdego napotkanego oddzielnego klucza.The GroupBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) method returns a collection of IGrouping<TKey,TElement> objects, one for each distinct key that was encountered. IGrouping<TKey,TElement>Jest to IEnumerable<T> również klucz skojarzony z jego elementami.An IGrouping<TKey,TElement> is an IEnumerable<T> that also has a key associated with its elements.

IGrouping<TKey,TElement>Obiekty są uzyskiwane w kolejności na podstawie kolejności elementów w programie source , która wygenerowała pierwszy klucz każdego z nich IGrouping<TKey,TElement> .The IGrouping<TKey,TElement> objects are yielded in an order based on the order of the elements in source that produced the first key of each IGrouping<TKey,TElement>. Elementy w grupowaniu są realizowane w kolejności, w której się znajdują source .Elements in a grouping are yielded in the order they appear in source.

Jeśli comparer jest null , domyślną funkcję porównującą równość Default używa się do porównywania kluczy.If comparer is null, the default equality comparer Default is used to compare keys.

Jeśli dwa klucze są uważane za równe comparer , pierwszy klucz jest wybierany jako klucz dla tego grupowania.If two keys are considered equal according to comparer, the first key is chosen as the key for that grouping.

W składni wyrażenia zapytania, group by klauzula (Visual C#) lub Group By Into (Visual Basic) tłumaczy na wywołanie GroupBy .In query expression syntax, a group by (Visual C#) or Group By Into (Visual Basic) clause translates to an invocation of GroupBy. Aby uzyskać więcej informacji i przykłady użycia, zobacz klauzula Group i klauzula GROUP by.For more information and usage examples, see group clause and Group By Clause.