Enumerable.ToLookup Method

Definition

Cria um Lookup<TKey,TElement> genérico de um IEnumerable<T>.Creates a generic Lookup<TKey,TElement> from an IEnumerable<T>.

Overloads

ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>)

Cria um Lookup<TKey,TElement> de um IEnumerable<T>, de acordo com as funções especificadas de seletor de chave e seletor de elemento.Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to specified key selector and element selector functions.

ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>)

Cria um Lookup<TKey,TElement> de um IEnumerable<T> de acordo com uma função de seletor de chave, um comparador e uma função de seletor de elemento especificados.Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to a specified key selector function, a comparer and an element selector function.

ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)

Cria um Lookup<TKey,TElement> de um IEnumerable<T>, de acordo com uma função de seletor de chave especificada.Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to a specified key selector function.

ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>)

Cria um Lookup<TKey,TElement> de um IEnumerable<T>, de acordo com uma função de seletor de chave especificada e um comparador de chaves.Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to a specified key selector function and key comparer.

ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>)

Cria um Lookup<TKey,TElement> de um IEnumerable<T>, de acordo com as funções especificadas de seletor de chave e seletor de elemento.Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to specified key selector and element selector functions.

public:
generic <typename TSource, typename TKey, typename TElement>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::ILookup<TKey, TElement> ^ ToLookup(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, Func<TSource, TElement> ^ elementSelector);
public static System.Linq.ILookup<TKey,TElement> ToLookup<TSource,TKey,TElement> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TSource,TElement> elementSelector);
static member ToLookup : seq<'Source> * Func<'Source, 'Key> * Func<'Source, 'Element> -> System.Linq.ILookup<'Key, 'Element>
<Extension()>
Public Function ToLookup(Of TSource, TKey, TElement) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), elementSelector As Func(Of TSource, TElement)) As ILookup(Of TKey, TElement)

Type Parameters

TSource

O tipo dos elementos de source.The type of the elements of source.

TKey

O tipo da chave retornada por keySelector.The type of the key returned by keySelector.

TElement

O tipo do valor retornado por elementSelector.The type of the value returned by elementSelector.

Parameters

source
IEnumerable<TSource>

O IEnumerable<T> por meio do qual um Lookup<TKey,TElement> será criado.The IEnumerable<T> to create a Lookup<TKey,TElement> from.

keySelector
Func<TSource,TKey>

Uma função para extrair uma chave de cada elemento.A function to extract a key from each element.

elementSelector
Func<TSource,TElement>

Uma função de transformação para produzir um valor de elemento de resultado de cada elemento.A transform function to produce a result element value from each element.

Returns

ILookup<TKey,TElement>

Um Lookup<TKey,TElement> que contém valores do tipo TElement selecionados da sequência de entrada.A Lookup<TKey,TElement> that contains values of type TElement selected from the input sequence.

Exceptions

source, keySelector ou elementSelector é null.source or keySelector or elementSelector is null.

Examples

O exemplo de código a seguir demonstra como usar ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) para criar um Lookup<TKey,TElement> usando uma função de seletor de chave e uma função de seletor de elemento.The following code example demonstrates how to use ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) to create a Lookup<TKey,TElement> by using a key selector function and an element selector function.

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
    public long TrackingNumber { get; set; }
}

public static void ToLookupEx1()
{
    // Create a list of Packages.
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard",
                  Weight = 25.2, TrackingNumber = 89453312L },
              new Package { Company = "Lucerne Publishing",
                  Weight = 18.7, TrackingNumber = 89112755L },
              new Package { Company = "Wingtip Toys",
                  Weight = 6.0, TrackingNumber = 299456122L },
              new Package { Company = "Contoso Pharmaceuticals",
                  Weight = 9.3, TrackingNumber = 670053128L },
              new Package { Company = "Wide World Importers",
                  Weight = 33.8, TrackingNumber = 4665518773L } };

    // Create a Lookup to organize the packages.
    // Use the first character of Company as the key value.
    // Select Company appended to TrackingNumber
    // as the element values of the Lookup.
    ILookup<char, string> lookup =
        packages
        .ToLookup(p => Convert.ToChar(p.Company.Substring(0, 1)),
                  p => p.Company + " " + p.TrackingNumber);

    // Iterate through each IGrouping in the Lookup.
    foreach (IGrouping<char, string> packageGroup in lookup)
    {
        // Print the key value of the IGrouping.
        Console.WriteLine(packageGroup.Key);
        // Iterate through each value in the
        // IGrouping and print its value.
        foreach (string str in packageGroup)
            Console.WriteLine("    {0}", str);
    }
}

/*
 This code produces the following output:

 C
     Coho Vineyard 89453312
     Contoso Pharmaceuticals 670053128
 L
     Lucerne Publishing 89112755
 W
     Wingtip Toys 299456122
     Wide World Importers 4665518773
*/
Structure Package
    Public Company As String
    Public Weight As Double
    Public TrackingNumber As Long
End Structure

Sub ToLookupEx1()
    ' Create a list of Packages.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With
      {.Company = "Coho Vineyard", .Weight = 25.2, .TrackingNumber = 89453312L},
      New Package With
      {.Company = "Lucerne Publishing", .Weight = 18.7, .TrackingNumber = 89112755L},
      New Package With
      {.Company = "Wingtip Toys", .Weight = 6.0, .TrackingNumber = 299456122L},
      New Package With
      {.Company = "Contoso Pharmaceuticals", .Weight = 9.3, .TrackingNumber = 670053128L},
      New Package With
      {.Company = "Wide World Importers", .Weight = 33.8, .TrackingNumber = 4665518773L}})

    ' Create a Lookup to organize the packages. 
    ' Use the first character of Company as the key value.
    ' Select Company appended to TrackingNumber 
    ' as the element values of the Lookup.
    Dim lookup As ILookup(Of Char, String) =
    packages.ToLookup(Function(p) _
                          Convert.ToChar(p.Company.Substring(0, 1)),
                      Function(p) _
                          p.Company & " " & p.TrackingNumber)

    Dim output As New System.Text.StringBuilder

    ' Iterate through each IGrouping in the Lookup.
    For Each packageGroup As IGrouping(Of Char, String) In lookup
        ' Print the key value of the IGrouping.
        output.AppendLine(packageGroup.Key)
        ' Iterate through each value in the IGrouping and print its value.
        For Each str As String In packageGroup
            output.AppendLine("   " & str)
        Next
    Next

    ' Select a group of packages by indexing directly into the Lookup.
    Dim cgroup As IEnumerable(Of String) = lookup("C"c)

    output.AppendLine(vbCrLf & "Packages from Company names that start with 'C':")
    For Each str As String In cgroup
        output.AppendLine(str)
    Next

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

' This code produces the following output:
'
' C
'    Coho Vineyard 89453312
'    Contoso Pharmaceuticals 670053128
' L
'    Lucerne Publishing 89112755
' W
'    Wingtip Toys 299456122
'    Wide World Importers 4665518773
'
' Packages from Company names that start with 'C':
' Coho Vineyard 89453312
' Contoso Pharmaceuticals 670053128

Remarks

O método ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) retorna um Lookup<TKey,TElement>, um dicionário de um para muitos que mapeia chaves para coleções de valores.The ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) method returns a Lookup<TKey,TElement>, a one-to-many dictionary that maps keys to collections of values. Uma Lookup<TKey,TElement> difere de uma Dictionary<TKey,TValue>, que executa um mapeamento um-para-um de chaves para valores únicos.A Lookup<TKey,TElement> differs from a Dictionary<TKey,TValue>, which performs a one-to-one mapping of keys to single values.

O Default de comparação de igualdade padrão é usado para comparar chaves.The default equality comparer Default is used to compare keys.

ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>)

Cria um Lookup<TKey,TElement> de um IEnumerable<T> de acordo com uma função de seletor de chave, um comparador e uma função de seletor de elemento especificados.Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to a specified key selector function, a comparer and an element selector function.

public:
generic <typename TSource, typename TKey, typename TElement>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::ILookup<TKey, TElement> ^ ToLookup(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, Func<TSource, TElement> ^ elementSelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);
public static System.Linq.ILookup<TKey,TElement> ToLookup<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 ToLookup : seq<'Source> * Func<'Source, 'Key> * Func<'Source, 'Element> * System.Collections.Generic.IEqualityComparer<'Key> -> System.Linq.ILookup<'Key, 'Element>
<Extension()>
Public Function ToLookup(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 ILookup(Of TKey, TElement)

Type Parameters

TSource

O tipo dos elementos de source.The type of the elements of source.

TKey

O tipo da chave retornada por keySelector.The type of the key returned by keySelector.

TElement

O tipo do valor retornado por elementSelector.The type of the value returned by elementSelector.

Parameters

source
IEnumerable<TSource>

O IEnumerable<T> por meio do qual um Lookup<TKey,TElement> será criado.The IEnumerable<T> to create a Lookup<TKey,TElement> from.

keySelector
Func<TSource,TKey>

Uma função para extrair uma chave de cada elemento.A function to extract a key from each element.

elementSelector
Func<TSource,TElement>

Uma função de transformação para produzir um valor de elemento de resultado de cada elemento.A transform function to produce a result element value from each element.

comparer
IEqualityComparer<TKey>

Um IEqualityComparer<T> para comparar chaves.An IEqualityComparer<T> to compare keys.

Returns

ILookup<TKey,TElement>

Um Lookup<TKey,TElement> que contém valores do tipo TElement selecionados da sequência de entrada.A Lookup<TKey,TElement> that contains values of type TElement selected from the input sequence.

Exceptions

source, keySelector ou elementSelector é null.source or keySelector or elementSelector is null.

Remarks

O método ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>) retorna um Lookup<TKey,TElement>, um dicionário de um para muitos que mapeia chaves para coleções de valores.The ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>) method returns a Lookup<TKey,TElement>, a one-to-many dictionary that maps keys to collections of values. Uma Lookup<TKey,TElement> difere de uma Dictionary<TKey,TValue>, que executa um mapeamento um-para-um de chaves para valores únicos.A Lookup<TKey,TElement> differs from a Dictionary<TKey,TValue>, which performs a one-to-one mapping of keys to single values.

Se comparer for null, o comparador de igualdade padrão Default será usado para comparar as chaves.If comparer is null, the default equality comparer Default is used to compare keys.

ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)

Cria um Lookup<TKey,TElement> de um IEnumerable<T>, de acordo com uma função de seletor de chave especificada.Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to a specified key selector function.

public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::ILookup<TKey, TSource> ^ ToLookup(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector);
public static System.Linq.ILookup<TKey,TSource> ToLookup<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector);
static member ToLookup : seq<'Source> * Func<'Source, 'Key> -> System.Linq.ILookup<'Key, 'Source>
<Extension()>
Public Function ToLookup(Of TSource, TKey) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey)) As ILookup(Of TKey, TSource)

Type Parameters

TSource

O tipo dos elementos de source.The type of the elements of source.

TKey

O tipo da chave retornada por keySelector.The type of the key returned by keySelector.

Parameters

source
IEnumerable<TSource>

O IEnumerable<T> por meio do qual um Lookup<TKey,TElement> será criado.The IEnumerable<T> to create a Lookup<TKey,TElement> from.

keySelector
Func<TSource,TKey>

Uma função para extrair uma chave de cada elemento.A function to extract a key from each element.

Returns

ILookup<TKey,TSource>

Um Lookup<TKey,TElement> que contém chaves e valores.A Lookup<TKey,TElement> that contains keys and values. Os valores dentro de cada grupo estão na mesma ordem que no source.The values within each group are in the same order as in source.

Exceptions

source ou keySelector é null.source or keySelector is null.

Remarks

O método ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) retorna um Lookup<TKey,TElement>, um dicionário de um para muitos que mapeia chaves para coleções de valores.The ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) method returns a Lookup<TKey,TElement>, a one-to-many dictionary that maps keys to collections of values. Uma Lookup<TKey,TElement> difere de uma Dictionary<TKey,TValue>, que executa um mapeamento um-para-um de chaves para valores únicos.A Lookup<TKey,TElement> differs from a Dictionary<TKey,TValue>, which performs a one-to-one mapping of keys to single values.

O Default de comparação de igualdade padrão é usado para comparar chaves.The default equality comparer Default is used to compare keys.

ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>)

Cria um Lookup<TKey,TElement> de um IEnumerable<T>, de acordo com uma função de seletor de chave especificada e um comparador de chaves.Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to a specified key selector function and key comparer.

public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::ILookup<TKey, TSource> ^ ToLookup(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);
public static System.Linq.ILookup<TKey,TSource> ToLookup<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);
static member ToLookup : seq<'Source> * Func<'Source, 'Key> * System.Collections.Generic.IEqualityComparer<'Key> -> System.Linq.ILookup<'Key, 'Source>
<Extension()>
Public Function ToLookup(Of TSource, TKey) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), comparer As IEqualityComparer(Of TKey)) As ILookup(Of TKey, TSource)

Type Parameters

TSource

O tipo dos elementos de source.The type of the elements of source.

TKey

O tipo da chave retornada por keySelector.The type of the key returned by keySelector.

Parameters

source
IEnumerable<TSource>

O IEnumerable<T> por meio do qual um Lookup<TKey,TElement> será criado.The IEnumerable<T> to create a Lookup<TKey,TElement> from.

keySelector
Func<TSource,TKey>

Uma função para extrair uma chave de cada elemento.A function to extract a key from each element.

comparer
IEqualityComparer<TKey>

Um IEqualityComparer<T> para comparar chaves.An IEqualityComparer<T> to compare keys.

Returns

ILookup<TKey,TSource>

Um Lookup<TKey,TElement> que contém chaves e valores.A Lookup<TKey,TElement> that contains keys and values. Os valores dentro de cada grupo estão na mesma ordem que no source.The values within each group are in the same order as in source.

Exceptions

source ou keySelector é null.source or keySelector is null.

Remarks

O método ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) retorna um Lookup<TKey,TElement>, um dicionário de um para muitos que mapeia chaves para coleções de valores.The ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) method returns a Lookup<TKey,TElement>, a one-to-many dictionary that maps keys to collections of values. Uma Lookup<TKey,TElement> é diferente de uma Dictionary<TKey,TValue>, que executa um mapeamento um-para-um de chaves para valores únicos.A Lookup<TKey,TElement> is different to a Dictionary<TKey,TValue>, which performs a one-to-one mapping of keys to single values.

Se comparer for null, o comparador de igualdade padrão Default será usado para comparar as chaves.If comparer is null, the default equality comparer Default is used to compare keys.

Applies to