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A set of extension methods for various .NET sequence types.
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ExtraLINQ

ExtraLINQ provides a set of extension methods for various .NET sequence types.

Installation

ExtraLINQ is available as a NuGet package:

Install-Package ExtraLINQ

Extensions

Extensions for collections of type IEnumerable<T>:

Extensions for collections of type NameValueCollection:

Extensions for IEnumerable<T>

Chunk

Splits the given sequence into chunks of the given size. If the sequence length isn't evenly divisible by the chunk size, the last chunk will contain all remaining elements.

int[] numbers = { 1, 2, 3, 4, 5, 6, 7 };
int[][] chunks = numbers.Chunk(3).ToArray();

// chunks = [[1, 2, 3], [4, 5, 6], [7]]

Cycle

Turns a finite sequence into a circular one, or equivalently, repeats the original sequence indefinitely.

int[] bits = { 0, 1 };
int[] alternatingBits = bits.Cycle().Take(5).ToArray();

// alternatingBits = [0, 1, 0, 1, 0]

Distinct

Returns distinct elements from the given sequence using the default equality comparer to compare projected values.

string[] spellingsOfJavaScript = { "JavaScript", "Javascript", "javascript" };
string[] distinctSpellings = spellingsOfJavaScript
    .Distinct(n => n.ToLower())
    .ToArray();

// distinctSpellings = ["JavaScript"]

Each

Passes every element of the sequence to the specified action and returns it afterwards.

string[] ringInscriptionLines =
{
    "One Ring to rule them all",
    "One Ring to find them",
    "One Ring to bring them all",
    "and in the darkness bind them"
};

ringInscriptionLines.Each(Console.WriteLine);

// Console output:
//
// One Ring to rule them all
// One Ring to find them
// One Ring to bring them all
// and in the darkness bind them

Flatten

Returns a flattened sequence that contains the concatenation of all the nested sequences' elements.

int[][] numbers =
{
    new[] { 1, 2, 3 },
    new[] { 4, 5 },
    new[] { 6 }
};

int[] flattenedNumbers = numbers.Flatten().ToArray();

// flattenedNumbers = [1, 2, 3, 4, 5, 6]

HasAtLeast

Determines whether a collection contains at least a certain number of items.

string[] theThreeRings = { "Narya", "Nenya", "Vilya" };

theThreeRings.HasAtLeast(0) // true
theThreeRings.HasAtLeast(2) // true
theThreeRings.HasAtLeast(4) // false

Optionally, a predicate can be passed that is called for every element:

string[] theThreeRings = { "Narya", "Nenya", "Vilya" };

theThreeRings.HasAtLeast(2, ring => ring.StartsWith("N")) // true
theThreeRings.HasAtLeast(3, ring => ring.StartsWith("N")) // false

HasAtMost

Determines whether a collection contains at most a certain number of items.

string[] theThreeRings = { "Narya", "Nenya", "Vilya" };

theThreeRings.HasAtMost(2) // false
theThreeRings.HasAtMost(3) // true
theThreeRings.HasAtMost(4) // true

Optionally, a predicate can be passed that is called for every element:

string[] theThreeRings = { "Narya", "Nenya", "Vilya" };

theThreeRings.HasAtMost(1, ring => ring.StartsWith("N")) // false
theThreeRings.HasAtMost(2, ring => ring.StartsWith("N")) // true

HasExactly

Determines whether a collection contains exactly a given number of items.

string[] theThreeRings = { "Narya", "Nenya", "Vilya" };

theThreeRings.HasExactly(2) // false
theThreeRings.HasExactly(3) // true
theThreeRings.HasExactly(4) // false

Optionally, a predicate can be passed that is called for every element:

string[] theThreeRings = { "Narya", "Nenya", "Vilya" };

theThreeRings.HasExactly(1, ring => ring.StartsWith("N")) // false
theThreeRings.HasExactly(1, ring => ring.StartsWith("V")) // true
theThreeRings.HasExactly(2, ring => ring.StartsWith("N")) // true

Intersperse

Returns all elements of the collection separated by the given separator.

int[] numbers = { 1, 2, 3, 4, 5 };
int[] separatedNumbers = numbers.Intersperse(0).ToArray();

// separatedNumbers = [1, 0, 2, 0, 3, 0, 4, 0, 5]

IsEmpty

Determines whether a collection is empty.

new int[0].IsEmpty() // true
new[] { 1, 2, 3 }.IsEmpty() // false

IsNullOrEmpty

Determines whether a collection is null or empty.

(null as int[]).IsNullOrEmpty() // true
new int[0].IsNullOrEmpty() // true
new[] { 1, 2, 3 }.IsNullOrEmpty() // false

JoinedBy

Concatenates all items of a sequence using the specified separator between each item.

string[] nameParts = { "The", "One", "Ring" };
string ringName = nameParts
    .Select(part => part.ToUpper())
    .JoinedBy(" ");

// ringName = "THE ONE RING"

Note that the main purpose of JoinedBy is to provide a chainable wrapper around String.Join.

None

Determines whether a collection doesn't contain any elements matching certain criteria.

string[] theThreeRings = { "Narya", "Nenya", "Vilya" };
bool allRingsNamed = theThreeRings.None(string.IsNullOrWhiteSpace);

// allRingsNamed = true

The None method is equivalent to a negated version of Any.

Partition

Uses the given predicate to partition the given sequence into two sequences, one with all the matches and one with all the mismatches.

int[] numbers = { 1, 2, 3, 4, 5 };
var partitionedNumbers = numbers.Partition(n => n % 2 == 0);

// partitionedNumbers.Matches = [2, 4]
// partitionedNumbers.Mismatches = [1, 3, 5]

Random

Returns a given number of random elements from a collection.

int[] numbers = Enumerable.Range(1, 49).ToArray();
int[] lottoNumbers = numbers
    .Random(6)
    .OrderBy(n => n)
    .ToArray();

// e.g. lottoNumbers = [5, 19, 20, 27, 38, 41]

Repeat

Repeats a given sequence a given number of times.

string[] eatingSounds = { "om", "nom", "nom" };
string[] cookieMonsterSounds = eatingSounds.Repeat(3).JoinedBy(" ");

// cookieMonsterSounds = ["om", "nom", "nom", "om", "nom", "nom", "om", "nom", "nom"]

Shuffle

Enumerates the specified input sequence and returns a new sequence which contains all input elements in random order.

string[] hobbits = { "Frodo", "Sam", "Merry", "Pippin" };
string[] shuffledHobbits = hobbits.Shuffle().ToArray();

// e.g. shuffledHobbits = ["Sam", "Pippin", "Frodo", "Merry"]

TakeSkip

Iterates over the given sequence and repeatedly returns a specified number of elements before skipping a specified number of elements.

string[] fellowship =
{
    "Frodo",
    "Sam",
    "Merry",
    "Pippin",
    "Aragorn",
    "Legolas",
    "Gimli",
    "Boromir",
    "Gandalf"
};

string[] everyOtherFellow = fellowship.TakeSkip(1, 1).ToArray();

// everyOtherFellow = ["Frodo", "Merry", "Aragorn", "Gimli", "Gandalf"]

ToHashSet

Creates a HashSet from a given sequence.

string gollumsUtterings = "Nasty hobbitses, gollum, gollum!";
HashSet<string> gollumsVocabulary = gollumsUtterings
    .Split(new[] { ' ', ',', '!' }, StringSplitOptions.RemoveEmptyEntries)
    .ToHashSet();

// gollumsVocabulary = ["Nasty", "hobbitses", "gollum"]

Note that the main purpose of ToHashSet is to provide a chainable wrapper around the HashSet constructor.

WhereNot

Filters a sequence of values based on a given predicate and returns those values that don't match the predicate.

string[] theThreeRings = { "Narya", "Nenya", "Vilya" };
Func<string, bool> startsWithN = value => value.StartsWith("N");
string vilya = theThreeRings.WhereNot(startsWithN).Single();

// vilya = "Vilya"

Without

Returns the specified collection without the specified items.

string[] hobbits = { "Frodo", "Sam", "Merry", "Pippin" };
string[] mainHobbits = hobbits.Without("Merry", "Pippin").ToArray();

// mainHobbits = ["Frodo", "Sam"]

Extensions for NameValueCollection

ToDictionary

Returns a new dictionary from the specified collection.

var ringBearers = new NameValueCollection
{
    { "Nenya", "Galadriel" },
    { "Narya", "Gandalf" },
    { "Vilya", "Elrond" }
};

Dictionary<string, string> ringBearersDictionary = ringBearers.ToDictionary();

ToKeyValuePairs

Enumerates the specified collection as a sequence of key-value pairs.

var ringBearers = new NameValueCollection
{
    { "Nenya", "Galadriel" },
    { "Narya", "Gandalf" },
    { "Vilya", "Elrond" }
};

IEnumerable<KeyValuePair<string, string>> ringBearersKeyValuePairs = ringBearers.ToKeyValuePairs();
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