Method RunLengthEncode

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RunLengthEncode<T>(IEnumerable<T>)

Run-length encodes a sequence by converting consecutive instances of the same element into a tuple representing the item and its occurrence count.

Declaration
public static IEnumerable<(T value, int count)> RunLengthEncode<T>(this IEnumerable<T> sequence)
Parameters
Type Name Description
IEnumerable<T> sequence

The sequence to run length encode
Returns
Type Description
IEnumerable<(T value, int count)>

A sequence of tuples containing the element and the occurrence count
Type Parameters
Name Description
T

The type of the elements in the sequence
Remarks

This operator evaluates in a deferred and streaming manner.

Examples

The following code example demonstrates how to return the run-length-encoding of a sequence using RunLengthEncode.

var sequence = Enumerable.Repeat(1, 3)
    .Concat(Enumerable.Repeat(2, 4))
    .Concat(Enumerable.Repeat(3, 2));

// Get the run-length encoding of a sequence
var result = sequence.RunLengthEncode();

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

// This code produces the following output:
// [(1, 3), (2, 4), (3, 2)]
Exceptions
Type Condition
ArgumentNullException

sequence is null.
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RunLengthEncode<T>(IEnumerable<T>, IEqualityComparer<T>?)

Run-length encodes a sequence by converting consecutive instances of the same element into a tuple representing the item and its occurrence count. This overload uses a custom equality comparer to identify equivalent items.

Declaration
public static IEnumerable<(T value, int count)> RunLengthEncode<T>(this IEnumerable<T> sequence, IEqualityComparer<T>? comparer)
Parameters
Type Name Description
IEnumerable<T> sequence

The sequence to run length encode
IEqualityComparer<T> comparer

The comparer used to identify equivalent items
Returns
Type Description
IEnumerable<(T value, int count)>

A sequence of tuples containing the element and the occurrence count
Type Parameters
Name Description
T

The type of the elements in the sequence
Remarks

This operator evaluates in a deferred and streaming manner.

Examples

The following code example demonstrates how to return the run-length-encoding of a sequence using RunLengthEncode.

var sequence = new[]
{
    "foo",
    "FOO",
    "fOo",
    "bAr",
    "BAR",
    "BAZ",
    "baz",
    "Baz",
    "BaZ",
    "Qux",
};

// Get the run-length encoding of a sequence
var result = sequence
    .RunLengthEncode(
        StringComparer.OrdinalIgnoreCase);

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

// This code produces the following output:
// [(foo, 3), (bAr, 2), (BAZ, 4), (Qux, 1)]
Exceptions
Type Condition
ArgumentNullException

sequence is null.