Enumerable.ThenByDescending Enumerable.ThenByDescending Enumerable.ThenByDescending Enumerable.ThenByDescending Method

定義

シーケンス内の後続の要素を降順で配置します。Performs a subsequent ordering of the elements in a sequence in descending order.

オーバーロード

ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>)

キーに従って、シーケンス内の後続の要素を降順で配置します。Performs a subsequent ordering of the elements in a sequence in descending order, according to a key.

ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)

指定された比較子を使用して、シーケンス内の後続の要素を降順で配置します。Performs a subsequent ordering of the elements in a sequence in descending order by using a specified comparer.

ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>)

キーに従って、シーケンス内の後続の要素を降順で配置します。Performs a subsequent ordering of the elements in a sequence in descending order, according to a key.

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

型パラメーター

TSource

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

TKey

keySelector によって返されるキーの型。The type of the key returned by keySelector.

パラメーター

source
IOrderedEnumerable<TSource>

並べ替える要素を格納している IOrderedEnumerable<TElement>An IOrderedEnumerable<TElement> that contains elements to sort.

keySelector
Func<TSource,TKey>

各要素からキーを抽出する関数。A function to extract a key from each element.

戻り値

要素がキーに従って降順に並べ替えられている IOrderedEnumerable<TElement>An IOrderedEnumerable<TElement> whose elements are sorted in descending order according to a key.

例外

source または keySelectornull です。source or keySelector 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. 即時の戻り値は、操作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.

を、要素自体の値によって、シーケンスを順序付けるに identity 関数を指定します (x => x Visual C# またはFunction(x) xVisual Basic) のkeySelectorTo order a sequence by the values of the elements themselves, specify the identity function (x => x in Visual C# or Function(x) x in Visual Basic) for keySelector.

ThenBy ThenByDescending型を拡張するよう定義はIOrderedEnumerable<TElement>、これらのメソッドの戻り値の型でもあります。ThenBy and ThenByDescending are defined to extend the type IOrderedEnumerable<TElement>, which is also the return type of these methods. この設計では、任意の数を適用することで複数の並べ替え条件を指定できます。ThenByまたはThenByDescendingメソッド。This design enables you to specify multiple sort criteria by applying any number of ThenBy or ThenByDescending methods.

注意

IOrderedEnumerable<TElement>継承IEnumerable<T>、呼び出すことができますOrderByまたはOrderByDescendingへの呼び出しの結果にOrderByOrderByDescendingThenByまたはThenByDescendingします。Because IOrderedEnumerable<TElement> inherits from IEnumerable<T>, you can call OrderBy or OrderByDescending on the results of a call to OrderBy, OrderByDescending, ThenBy or ThenByDescending. これを行うには、新しいプライマリ順序を以前に確立された順序を無視するが導入されています。Doing this introduces a new primary ordering that ignores the previously established ordering.

この並べ替え方法は、既定の比較子を使用してキーを比較Defaultします。This sorting method compares keys by using the default comparer Default.

このメソッドは、安定した並べ替え; を実行します。つまり、2 つの要素のキーが等しい場合は、要素の順序が保持されます。This method performs a stable sort; that is, if the keys of two elements are equal, the order of the elements is preserved. これに対し、不安定な並べ替えは、同じキーを持つ要素の順序は保持されません。In contrast, an unstable sort does not preserve the order of elements that have the same key.

クエリ式構文 (Visual C#) で、orderby [first criterion], [second criterion] descending句がの呼び出しに変換されますThenByDescendingします。In Visual C# query expression syntax, an orderby [first criterion], [second criterion] descending clause translates to an invocation of ThenByDescending.

Visual Basic のクエリ式の構文、Order By [first criterion], [second criterion] Descendingの呼び出しに変換句ThenByDescendingします。In Visual Basic query expression syntax, an Order By [first criterion], [second criterion] Descending clause translates to an invocation of ThenByDescending.

こちらもご覧ください

ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)

指定された比較子を使用して、シーケンス内の後続の要素を降順で配置します。Performs a subsequent ordering of the elements in a sequence in descending order by using a specified comparer.

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

型パラメーター

TSource

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

TKey

keySelector によって返されるキーの型。The type of the key returned by keySelector.

パラメーター

source
IOrderedEnumerable<TSource>

並べ替える要素を格納している IOrderedEnumerable<TElement>An IOrderedEnumerable<TElement> that contains elements to sort.

keySelector
Func<TSource,TKey>

各要素からキーを抽出する関数。A function to extract a key from each element.

comparer
IComparer<TKey>

キーを比較する IComparer<T>An IComparer<T> to compare keys.

戻り値

要素がキーに従って降順に並べ替えられている IOrderedEnumerable<TElement>An IOrderedEnumerable<TElement> whose elements are sorted in descending order according to a key.

例外

source または keySelectornull です。source or keySelector is null.

次のコード例は、使用する方法を示しますThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)カスタム比較子を使用して、降順のシーケンス内の要素の 2 番目の並べ替えを実行します。The following code example demonstrates how to use ThenByDescending<TSource,TKey>(IOrderedEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) to perform a secondary ordering of the elements in a sequence in descending order by using a custom comparer.

public class CaseInsensitiveComparer : IComparer<string>
{
    public int Compare(string x, string y)
    {
        return string.Compare(x, y, true);
    }
}

public static void ThenByDescendingEx1()
{
    string[] fruits = { "apPLe", "baNanA", "apple", "APple", "orange", "BAnana", "ORANGE", "apPLE" };

    // Sort the strings first ascending by their length and 
    // then descending using a custom case insensitive comparer.
    IEnumerable<string> query =
        fruits
        .OrderBy(fruit => fruit.Length)
        .ThenByDescending(fruit => fruit, new CaseInsensitiveComparer());

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

/*
    This code produces the following output:

    apPLe
    apple
    APple
    apPLE
    orange
    ORANGE
    baNanA
    BAnana
*/
' This class provides a custom implementation of the Compare() method.
Class CaseInsensitiveComparer
    Implements IComparer(Of String)

    Function Compare(ByVal x As String, ByVal y As String) As Integer _
    Implements IComparer(Of String).Compare

        ' Compare values and ignore case.
        Return String.Compare(x, y, True)
    End Function
End Class

Sub ThenByDescendingEx1()
    Dim fruits() As String =
    {"apPLe", "baNanA", "apple", "APple", "orange", "BAnana", "ORANGE", "apPLE"}

    ' Sort the strings first by their length and then 
    ' by using a custom "case insensitive" comparer.
    Dim query As IEnumerable(Of String) =
    fruits _
    .OrderBy(Function(fruit) fruit.Length) _
    .ThenByDescending(Function(fruit) fruit, New CaseInsensitiveComparer())

    ' Display the results.
    Dim output As New System.Text.StringBuilder
    For Each fruit As String In query
        output.AppendLine(fruit)
    Next
    MsgBox(output.ToString())
End Sub

' This code produces the following output:

' apPLe
' apple
' APple
' apPLE
' orange
' ORANGE
' baNanA
' BAnana

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. 即時の戻り値は、操作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.

を、要素自体の値によって、シーケンスを順序付けるに identity 関数を指定します (x => x Visual C# またはFunction(x) xVisual Basic) のkeySelectorTo order a sequence by the values of the elements themselves, specify the identity function (x => x in Visual C# or Function(x) x in Visual Basic) for keySelector.

ThenBy ThenByDescending型を拡張するよう定義はIOrderedEnumerable<TElement>、これらのメソッドの戻り値の型でもあります。ThenBy and ThenByDescending are defined to extend the type IOrderedEnumerable<TElement>, which is also the return type of these methods. この設計では、任意の数を適用することで複数の並べ替え条件を指定できます。ThenByまたはThenByDescendingメソッド。This design enables you to specify multiple sort criteria by applying any number of ThenBy or ThenByDescending methods.

注意

IOrderedEnumerable<TElement>継承IEnumerable<T>、呼び出すことができますOrderByまたはOrderByDescendingへの呼び出しの結果にOrderByOrderByDescendingThenByまたはThenByDescendingします。Because IOrderedEnumerable<TElement> inherits from IEnumerable<T>, you can call OrderBy or OrderByDescending on the results of a call to OrderBy, OrderByDescending, ThenBy or ThenByDescending. これを行うには、新しいプライマリ順序を以前に確立された順序を無視するが導入されています。Doing this introduces a new primary ordering that ignores the previously established ordering.

場合comparernull、既定の比較子Defaultキーを比較するために使用します。If comparer is null, the default comparer Default is used to compare keys.

このメソッドは、安定した並べ替え; を実行します。つまり、2 つの要素のキーが等しい場合は、要素の順序が保持されます。This method performs a stable sort; that is, if the keys of two elements are equal, the order of the elements is preserved. これに対し、不安定な並べ替えは、同じキーを持つ要素の順序は保持されません。In contrast, an unstable sort does not preserve the order of elements that have the same key.

適用対象