Enumerable.Aggregate Method
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Aggregate<TSource,TAccumulate,TResult>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>, Func<TAccumulate,TResult>) |
Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value. |
Aggregate<TSource,TAccumulate>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>) |
Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value. |
Aggregate<TSource>(IEnumerable<TSource>, Func<TSource,TSource,TSource>) |
Applies an accumulator function over a sequence. |
Aggregate<TSource,TAccumulate,TResult>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>, Func<TAccumulate,TResult>)
- Source:
- Aggregate.cs
- Source:
- Aggregate.cs
- Source:
- Aggregate.cs
Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value.
public:
generic <typename TSource, typename TAccumulate, typename TResult>
[System::Runtime::CompilerServices::Extension]
static TResult Aggregate(System::Collections::Generic::IEnumerable<TSource> ^ source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> ^ func, Func<TAccumulate, TResult> ^ resultSelector);
public static TResult Aggregate<TSource,TAccumulate,TResult> (this System.Collections.Generic.IEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate,TSource,TAccumulate> func, Func<TAccumulate,TResult> resultSelector);
static member Aggregate : seq<'Source> * 'Accumulate * Func<'Accumulate, 'Source, 'Accumulate> * Func<'Accumulate, 'Result> -> 'Result
<Extension()>
Public Function Aggregate(Of TSource, TAccumulate, TResult) (source As IEnumerable(Of TSource), seed As TAccumulate, func As Func(Of TAccumulate, TSource, TAccumulate), resultSelector As Func(Of TAccumulate, TResult)) As TResult
Type Parameters
- TSource
The type of the elements of source
.
- TAccumulate
The type of the accumulator value.
- TResult
The type of the resulting value.
Parameters
- source
- IEnumerable<TSource>
An IEnumerable<T> to aggregate over.
- seed
- TAccumulate
The initial accumulator value.
- func
- Func<TAccumulate,TSource,TAccumulate>
An accumulator function to be invoked on each element.
- resultSelector
- Func<TAccumulate,TResult>
A function to transform the final accumulator value into the result value.
Returns
The transformed final accumulator value.
Exceptions
source
or func
or resultSelector
is null
.
Examples
The following code example demonstrates how to use Aggregate to apply an accumulator function and a result selector.
string[] fruits = { "apple", "mango", "orange", "passionfruit", "grape" };
// Determine whether any string in the array is longer than "banana".
string longestName =
fruits.Aggregate("banana",
(longest, next) =>
next.Length > longest.Length ? next : longest,
// Return the final result as an upper case string.
fruit => fruit.ToUpper());
Console.WriteLine(
"The fruit with the longest name is {0}.",
longestName);
// This code produces the following output:
//
// The fruit with the longest name is PASSIONFRUIT.
Sub AggregateEx3()
Dim fruits() As String =
{"apple", "mango", "orange", "passionfruit", "grape"}
' Determine whether any string in the array is longer than "banana".
Dim longestName As String =
fruits.Aggregate("banana",
Function(ByVal longest, ByVal fruit) _
IIf(fruit.Length > longest.Length, fruit, longest),
Function(ByVal fruit) fruit.ToUpper())
' Display the output.
Console.WriteLine($"The fruit with the longest name is {longestName}")
End Sub
' This code produces the following output:
'
' The fruit with the longest name is PASSIONFRUIT
Remarks
The Aggregate<TSource,TAccumulate,TResult>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>, Func<TAccumulate,TResult>) method makes it simple to perform a calculation over a sequence of values. This method works by calling func
one time for each element in source
. Each time func
is called, Aggregate<TSource,TAccumulate,TResult>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>, Func<TAccumulate,TResult>) passes both the element from the sequence and an aggregated value (as the first argument to func
). The value of the seed
parameter is used as the initial aggregate value. The result of func
replaces the previous aggregated value. The final result of func
is passed to resultSelector
to obtain the final result of Aggregate<TSource,TAccumulate,TResult>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>, Func<TAccumulate,TResult>).
To simplify common aggregation operations, the standard query operators also include a general purpose count method, Count, and four numeric aggregation methods, namely Min, Max, Sum, and Average.
Applies to
.NET 9 та інші версії
Продукт | Версії |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
Aggregate<TSource,TAccumulate>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>)
- Source:
- Aggregate.cs
- Source:
- Aggregate.cs
- Source:
- Aggregate.cs
Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value.
public:
generic <typename TSource, typename TAccumulate>
[System::Runtime::CompilerServices::Extension]
static TAccumulate Aggregate(System::Collections::Generic::IEnumerable<TSource> ^ source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> ^ func);
public static TAccumulate Aggregate<TSource,TAccumulate> (this System.Collections.Generic.IEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate,TSource,TAccumulate> func);
static member Aggregate : seq<'Source> * 'Accumulate * Func<'Accumulate, 'Source, 'Accumulate> -> 'Accumulate
<Extension()>
Public Function Aggregate(Of TSource, TAccumulate) (source As IEnumerable(Of TSource), seed As TAccumulate, func As Func(Of TAccumulate, TSource, TAccumulate)) As TAccumulate
Type Parameters
- TSource
The type of the elements of source
.
- TAccumulate
The type of the accumulator value.
Parameters
- source
- IEnumerable<TSource>
An IEnumerable<T> to aggregate over.
- seed
- TAccumulate
The initial accumulator value.
- func
- Func<TAccumulate,TSource,TAccumulate>
An accumulator function to be invoked on each element.
Returns
The final accumulator value.
Exceptions
source
or func
is null
.
Examples
The following code example demonstrates how to use Aggregate to apply an accumulator function and use a seed value.
int[] ints = { 4, 8, 8, 3, 9, 0, 7, 8, 2 };
// Count the even numbers in the array, using a seed value of 0.
int numEven = ints.Aggregate(0, (total, next) =>
next % 2 == 0 ? total + 1 : total);
Console.WriteLine("The number of even integers is: {0}", numEven);
// This code produces the following output:
//
// The number of even integers is: 6
Sub AggregateEx2()
' Create an array of Integers.
Dim ints() As Integer = {4, 8, 8, 3, 9, 0, 7, 8, 2}
' Count the even numbers in the array, using a seed value of 0.
Dim numEven As Integer =
ints.Aggregate(0,
Function(ByVal total, ByVal number) _
IIf(number Mod 2 = 0, total + 1, total))
' Display the output.
Console.WriteLine($"The number of even integers is {numEven}")
End Sub
' This code produces the following output:
'
'The number of even integers is 6
Remarks
The Aggregate<TSource,TAccumulate>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>) method makes it simple to perform a calculation over a sequence of values. This method works by calling func
one time for each element in source
. Each time func
is called, Aggregate<TSource,TAccumulate>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>) passes both the element from the sequence and an aggregated value (as the first argument to func
). The value of the seed
parameter is used as the initial aggregate value. The result of func
replaces the previous aggregated value. Aggregate<TSource,TAccumulate>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>) returns the final result of func
.
To simplify common aggregation operations, the standard query operators also include a general purpose count method, Count, and four numeric aggregation methods, namely Min, Max, Sum, and Average.
Applies to
.NET 9 та інші версії
Продукт | Версії |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
- Source:
- Aggregate.cs
- Source:
- Aggregate.cs
- Source:
- Aggregate.cs
Applies an accumulator function over a sequence.
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static TSource Aggregate(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TSource, TSource> ^ func);
public static TSource Aggregate<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TSource,TSource> func);
static member Aggregate : seq<'Source> * Func<'Source, 'Source, 'Source> -> 'Source
<Extension()>
Public Function Aggregate(Of TSource) (source As IEnumerable(Of TSource), func As Func(Of TSource, TSource, TSource)) As TSource
Type Parameters
- TSource
The type of the elements of source
.
Parameters
- source
- IEnumerable<TSource>
An IEnumerable<T> to aggregate over.
- func
- Func<TSource,TSource,TSource>
An accumulator function to be invoked on each element.
Returns
The final accumulator value.
Exceptions
source
or func
is null
.
source
contains no elements.
Examples
The following code example demonstrates how to reverse the order of words in a string by using Aggregate.
string sentence = "the quick brown fox jumps over the lazy dog";
// Split the string into individual words.
string[] words = sentence.Split(' ');
// Prepend each word to the beginning of the
// new sentence to reverse the word order.
string reversed = words.Aggregate((workingSentence, next) =>
next + " " + workingSentence);
Console.WriteLine(reversed);
// This code produces the following output:
//
// dog lazy the over jumps fox brown quick the
Sub AggregateEx1()
Dim sentence As String =
"the quick brown fox jumps over the lazy dog"
' Split the string into individual words.
Dim words() As String = sentence.Split(" "c)
' Prepend each word to the beginning of the new sentence to reverse the word order.
Dim reversed As String =
words.Aggregate(Function(ByVal current, ByVal word) word & " " & current)
' Display the output.
Console.WriteLine(reversed)
End Sub
' This code produces the following output:
'
' dog lazy the over jumps fox brown quick the
Remarks
The Aggregate<TSource>(IEnumerable<TSource>, Func<TSource,TSource,TSource>) method makes it simple to perform a calculation over a sequence of values. This method works by calling func
one time for each element in source
except the first one. Each time func
is called, Aggregate<TSource>(IEnumerable<TSource>, Func<TSource,TSource,TSource>) passes both the element from the sequence and an aggregated value (as the first argument to func
). The first element of source
is used as the initial aggregate value. The result of func
replaces the previous aggregated value. Aggregate<TSource>(IEnumerable<TSource>, Func<TSource,TSource,TSource>) returns the final result of func
.
This overload of the Aggregate method isn't suitable for all cases because it uses the first element of source
as the initial aggregate value. You should choose another overload if the return value should include only the elements of source
that meet a certain condition. For example, this overload isn't reliable if you want to calculate the sum of the even numbers in source
. The result will be incorrect if the first element is odd instead of even.
To simplify common aggregation operations, the standard query operators also include a general purpose count method, Count, and four numeric aggregation methods, namely Min, Max, Sum, and Average.
Applies to
.NET 9 та інші версії
Продукт | Версії |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
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