Enumerable.MinBy Method

Definition

Namespace:

System.Linq

Assemblies:

netstandard.dll, System.Linq.dll

Overloads

Name	Description
MinBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)	Returns the minimum value in a generic sequence according to a specified key selector function.
MinBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)	Returns the minimum value in a generic sequence according to a specified key selector function and key comparer.

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

Source:

Min.cs

Returns the minimum value in a generic sequence according to a specified key selector function.

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

public static TSource? MinBy<TSource,TKey>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector);

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

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

Type Parameters

TSource

The type of the elements of source.

TKey

The type of key to compare elements by.

Parameters

source

IEnumerable<TSource>

A sequence of values to determine the minimum value of.

keySelector

Func<TSource,TKey>

A function to extract the key for each element.

Returns

TSource

The value with the minimum key in the sequence.

Exceptions

ArgumentNullException

source is null.

ArgumentException

No key extracted from source implements the IComparable or IComparable<T> interface.

InvalidOperationException

TSource is a primitive type and the source sequence is empty.

Examples

The following code example demonstrates how to use MinBy to find the minimum value in a collection based on a specific property.

(string Name, decimal Salary, int Age)[] employees =
{
    ("Mahmoud", 1000m, 22),
    ("John", 1200m, 28),
    ("Sara", 2000m, 32),
    ("Hadi", 1750m, 27),
    ("Lana", 1500m, 24),
    ("Luna", 1850m, 33)
};

// Get the youngest employee in the company.
var youngestEmployee = employees.MinBy(employee => employee.Age);

Console.WriteLine($"Name: {youngestEmployee.Name}, Age: {youngestEmployee.Age}, Salary: ${youngestEmployee.Salary}");

/*
This code produces the following output:

Name: Mahmoud, Age: 22, Salary: $1000
*/

</format>

Remarks

If the source sequence is empty, two possible outcomes are possible depending on the source type. If TSource is a nullable type, this method returns null. If TSource is a non-nullable struct, such as a primitive type, an InvalidOperationException is thrown.

If the source sequence contains only values that are null, this method returns null.

<format type="text/markdown">

MinBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)

Source:

Min.cs

Returns the minimum value in a generic sequence according to a specified key selector function and key comparer.

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

public static TSource? MinBy<TSource,TKey>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, System.Collections.Generic.IComparer<TKey>? comparer);

static member MinBy : seq<'Source> * Func<'Source, 'Key> * System.Collections.Generic.IComparer<'Key> -> 'Source

<Extension()>
Public Function MinBy(Of TSource, TKey) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), comparer As IComparer(Of TKey)) As TSource

Type Parameters

TSource

The type of the elements of source.

TKey

The type of key to compare elements by.

Parameters

source

IEnumerable<TSource>

A sequence of values to determine the minimum value of.

keySelector

Func<TSource,TKey>

A function to extract the key for each element.

comparer

IComparer<TKey>

The IComparer<T> to compare keys.

Returns

TSource

The value with the minimum key in the sequence.

Exceptions

ArgumentNullException

source is null.

ArgumentException

No key extracted from source implements the IComparable or IComparable<T> interface.

InvalidOperationException

TSource is a primitive type and the source sequence is empty.

Examples

The following code example demonstrates how to use MinBy with a custom comparer to ignore case sensitivity when checking for the minimum value.

(string Name, int Quantity)[] inventory =
{
    ("apple", 10),
    ("BANANA", 5),
    ("Cherry", 20)
};

// Find the product with the minimum name alphabetically, ignoring casing differences.
// 'a' is correctly identified as smaller than 'B' when case is ignored.
var minIgnoreCase = inventory.MinBy(item => item.Name, StringComparer.OrdinalIgnoreCase);
Console.WriteLine($"Case-insensitive comparison: {minIgnoreCase.Name}");

/*
This code produces the following output:

Case-insensitive comparison: apple
*/

</format>

Remarks

If the source sequence is empty, two possible outcomes are possible depending on the source type. If TSource is a nullable type, this method returns null. If TSource is a non-nullable struct, such as a primitive type, an InvalidOperationException is thrown.

If the source sequence contains only values that are null, this method returns null.

<format type="text/markdown">