Method Partition

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Partition<T>(IEnumerable<T>, Func<T, bool>)

Partitions or splits a sequence in two using a predicate.

Declaration
public static (IEnumerable<T> True, IEnumerable<T> False) Partition<T>(this IEnumerable<T> source, Func<T, bool> predicate)
Parameters
Type Name Description
IEnumerable<T> source

The source sequence.
Func<T, bool> predicate

The predicate function.
Returns
Type Description
(IEnumerable<T> True, IEnumerable<T> False)

A tuple of elements satisfying the predicate and those that do not, respectively.
Type Parameters
Name Description
T

Type of source elements.
Remarks

This method executes immediately.

Examples

The following code example demonstrates how to partition a sequence using Partition.

var sequence = Enumerable.Range(0, 10);

// Partition a sequence
var (evens, odds) = sequence
    .Partition(x => x % 2 == 0);

Console.WriteLine(
    "evens: [" +
    string.Join(", ", evens) +
    "]");

Console.WriteLine(
    "odds: [" +
    string.Join(", ", odds) +
    "]");

// This code produces the following output:
// evens: [0, 2, 4, 6, 8]
// odds: [1, 3, 5, 7, 9]
Exceptions
Type Condition
ArgumentNullException

source is null.
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Partition<T, TResult>(IEnumerable<T>, Func<T, bool>, Func<IEnumerable<T>, IEnumerable<T>, TResult>)

Partitions or splits a sequence in two using a predicate and then projects a result from the two.

Declaration
public static TResult Partition<T, TResult>(this IEnumerable<T> source, Func<T, bool> predicate, Func<IEnumerable<T>, IEnumerable<T>, TResult> resultSelector)
Parameters
Type Name Description
IEnumerable<T> source

The source sequence.
Func<T, bool> predicate

The predicate function.
Func<IEnumerable<T>, IEnumerable<T>, TResult> resultSelector

Function that projects the result from sequences of elements that satisfy the predicate and those that do not, respectively, passed as arguments.
Returns
Type Description
TResult

The return value from resultSelector.
Type Parameters
Name Description
T

Type of source elements.
TResult

Type of the result.
Remarks

This method executes immediately.

Examples

The following code example demonstrates how to partition a sequence using Partition.

var sequence = Enumerable.Range(0, 10);

// Partition a sequence
var (evens, odds) = sequence
    .Partition(x => x % 2 == 0, ValueTuple.Create);

Console.WriteLine(
    "evens: [" +
    string.Join(", ", evens) +
    "]");

Console.WriteLine(
    "odds: [" +
    string.Join(", ", odds) +
    "]");

// This code produces the following output:
// evens: [0, 2, 4, 6, 8]
// odds: [1, 3, 5, 7, 9]
Exceptions
Type Condition
ArgumentNullException

source, predicate, or resultSelector is null.