Method FullGroupJoin

FullGroupJoin<TFirst, TSecond, TKey>(IEnumerable<TFirst>, IEnumerable<TSecond>, Func<TFirst, TKey>, Func<TSecond, TKey>)

Performs a Full Group Join between the first and second sequences.

Declaration

public static IEnumerable<(TKey Key, IEnumerable<TFirst> First, IEnumerable<TSecond> Second)> FullGroupJoin<TFirst, TSecond, TKey>(this IEnumerable<TFirst> first, IEnumerable<TSecond> second, Func<TFirst, TKey> firstKeySelector, Func<TSecond, TKey> secondKeySelector)

Parameters

Type	Name	Description
IEnumerable<TFirst>	first	First sequence
IEnumerable<TSecond>	second	Second sequence
Func<TFirst, TKey>	firstKeySelector	The mapping from first sequence to key
Func<TSecond, TKey>	secondKeySelector	The mapping from second sequence to key

Returns

Type	Description
IEnumerable<(TKey Key, IEnumerable<TFirst> First, IEnumerable<TSecond> Second)>	A sequence of elements joined from first and second.

Type Parameters

Name	Description
TFirst	The type of the elements in the first input sequence
TSecond	The type of the elements in the second input sequence
TKey	The type of the key to use to join

Remarks

This operator uses deferred execution and streams the results. The results are yielded in the order of the elements found in the first sequence followed by those found only in the second. In addition, the callback responsible for projecting the results is supplied with sequences which preserve their source order.

Examples

The following code example demonstrates how to execute a full group join using FullGroupJoin

var people = new Person[]
{
    new("John Doe", 1),
    new("Jane Doe", 1),
    new("Lucy Ricardo", 2),
    new("Ricky Ricardo", 2),
    new("Fred Mertz", 3),
    new("Ethel Mertz", 3),
};

var pets = new Pet[]
{
    new("Bear", 3),
    new("Polly", 2),
    new("Minnie", 2),
    new("Mittens", 1),
    new("Patches", 1),
    new("Paws", 1),
};

var results = people
    .FullGroupJoin(
        pets,
        p => p.FamilyId,
        p => p.FamilyId);

foreach (var (familyId, familyPeople, familyPets) in results)
{
    var str1 = string.Join(", ", familyPeople.Select(p => p.Name));
    var str2 = string.Join(", ", familyPets.Select(p => p.Name));
    Console.WriteLine($"({familyId}, [{str1}], [{str2}])");
}

// This code produces the following output:
// (1, [John Doe, Jane Doe], [Mittens, Patches, Paws])
// (2, [Lucy Ricardo, Ricky Ricardo], [Polly, Minnie])
// (3, [Fred Mertz, Ethel Mertz], [Bear])


record Person(string Name, int FamilyId);
record Pet(string Name, int FamilyId);

Exceptions

Type	Condition
ArgumentNullException	first, second, firstKeySelector, or secondKeySelector is null.

FullGroupJoin<TFirst, TSecond, TKey>(IEnumerable<TFirst>, IEnumerable<TSecond>, Func<TFirst, TKey>, Func<TSecond, TKey>, IEqualityComparer<TKey>?)

Performs a Full Group Join between the first and second sequences.

Declaration

public static IEnumerable<(TKey Key, IEnumerable<TFirst> First, IEnumerable<TSecond> Second)> FullGroupJoin<TFirst, TSecond, TKey>(this IEnumerable<TFirst> first, IEnumerable<TSecond> second, Func<TFirst, TKey> firstKeySelector, Func<TSecond, TKey> secondKeySelector, IEqualityComparer<TKey>? comparer)

Parameters

Type	Name	Description
IEnumerable<TFirst>	first	First sequence
IEnumerable<TSecond>	second	Second sequence
Func<TFirst, TKey>	firstKeySelector	The mapping from first sequence to key
Func<TSecond, TKey>	secondKeySelector	The mapping from second sequence to key
IEqualityComparer<TKey>	comparer	The equality comparer to use to determine whether or not keys are equal. If null, the default equality comparer for TKey is used.

Returns

Type	Description
IEnumerable<(TKey Key, IEnumerable<TFirst> First, IEnumerable<TSecond> Second)>	A sequence of elements joined from first and second.

Type Parameters

Name	Description
TFirst	The type of the elements in the first input sequence
TSecond	The type of the elements in the second input sequence
TKey	The type of the key to use to join

Remarks

This operator uses deferred execution and streams the results. The results are yielded in the order of the elements found in the first sequence followed by those found only in the second. In addition, the callback responsible for projecting the results is supplied with sequences which preserve their source order.

Examples

The following code example demonstrates how to execute a full group join using FullGroupJoin

var people = new Person[]
{
    new("John Doe", 1),
    new("Jane Doe", 1),
    new("Lucy Ricardo", 2),
    new("Ricky Ricardo", 2),
    new("Fred Mertz", 3),
    new("Ethel Mertz", 3),
};

var pets = new Pet[]
{
    new("Bear", 103),
    new("Polly", 102),
    new("Minnie", 102),
    new("Mittens", 101),
    new("Patches", 101),
    new("Paws", 101),
};

var results = people
    .FullGroupJoin(
        pets,
        p => p.FamilyId,
        p => p.FamilyId,
        new IntBy100Comparer());

foreach (var (familyId, familyPeople, familyPets) in results)
{
    var str1 = string.Join(", ", familyPeople.Select(p => p.Name));
    var str2 = string.Join(", ", familyPets.Select(p => p.Name));
    Console.WriteLine($"({familyId}, [{str1}], [{str2}])");
}

// This code produces the following output:
// (1, [John Doe, Jane Doe], [Mittens, Patches, Paws])
// (2, [Lucy Ricardo, Ricky Ricardo], [Polly, Minnie])
// (3, [Fred Mertz, Ethel Mertz], [Bear])


record Person(string Name, int FamilyId);
record Pet(string Name, int FamilyId);

class IntBy100Comparer : IEqualityComparer<int>
{
    public bool Equals(int x, int y) =>
        x % 100 == y % 100;

    public int GetHashCode(int obj) =>
        (obj % 100).GetHashCode();
}

Exceptions

Type	Condition
ArgumentNullException	first, second, firstKeySelector, or secondKeySelector is null.

FullGroupJoin<TFirst, TSecond, TKey, TResult>(IEnumerable<TFirst>, IEnumerable<TSecond>, Func<TFirst, TKey>, Func<TSecond, TKey>, Func<TKey, IEnumerable<TFirst>, IEnumerable<TSecond>, TResult>)

Performs a full group-join between two sequences.

Declaration

public static IEnumerable<TResult> FullGroupJoin<TFirst, TSecond, TKey, TResult>(this IEnumerable<TFirst> first, IEnumerable<TSecond> second, Func<TFirst, TKey> firstKeySelector, Func<TSecond, TKey> secondKeySelector, Func<TKey, IEnumerable<TFirst>, IEnumerable<TSecond>, TResult> resultSelector)

Parameters

Type	Name	Description
IEnumerable<TFirst>	first	First sequence
IEnumerable<TSecond>	second	Second sequence
Func<TFirst, TKey>	firstKeySelector	The mapping from first sequence to key
Func<TSecond, TKey>	secondKeySelector	The mapping from second sequence to key
Func<TKey, IEnumerable<TFirst>, IEnumerable<TSecond>, TResult>	resultSelector	Function to apply to each pair of elements plus the key

Returns

Type	Description
IEnumerable<TResult>	A sequence of elements joined from first and second.

Type Parameters

Name	Description
TFirst	The type of the elements in the first input sequence
TSecond	The type of the elements in the second input sequence
TKey	The type of the key to use to join
TResult	The type of the elements of the resulting sequence

Remarks

This operator uses deferred execution and streams the results. The results are yielded in the order of the elements found in the first sequence followed by those found only in the second. In addition, the callback responsible for projecting the results is supplied with sequences which preserve their source order.

Examples

The following code example demonstrates how to execute a full group join using FullGroupJoin

var people = new Person[]
{
    new("John Doe", 1),
    new("Jane Doe", 1),
    new("Lucy Ricardo", 2),
    new("Ricky Ricardo", 2),
    new("Fred Mertz", 3),
    new("Ethel Mertz", 3),
};

var pets = new Pet[]
{
    new("Bear", 3),
    new("Polly", 2),
    new("Minnie", 2),
    new("Mittens", 1),
    new("Patches", 1),
    new("Paws", 1),
};

var results = people
    .FullGroupJoin(
        pets,
        p => p.FamilyId,
        p => p.FamilyId,
        (familyId, familyPeople, familyPets) =>
        {
            var str1 = string.Join(", ", familyPeople.Select(p => p.Name));
            var str2 = string.Join(", ", familyPets.Select(p => p.Name));
            return $"({familyId}, [{str1}], [{str2}])";
        });

foreach (var str in results)
    Console.WriteLine(str);

// This code produces the following output:
// (1, [John Doe, Jane Doe], [Mittens, Patches, Paws])
// (2, [Lucy Ricardo, Ricky Ricardo], [Polly, Minnie])
// (3, [Fred Mertz, Ethel Mertz], [Bear])


record Person(string Name, int FamilyId);
record Pet(string Name, int FamilyId);

Exceptions

Type	Condition
ArgumentNullException	first, second, firstKeySelector, secondKeySelector, or resultSelector is null.

FullGroupJoin<TFirst, TSecond, TKey, TResult>(IEnumerable<TFirst>, IEnumerable<TSecond>, Func<TFirst, TKey>, Func<TSecond, TKey>, Func<TKey, IEnumerable<TFirst>, IEnumerable<TSecond>, TResult>, IEqualityComparer<TKey>?)

Performs a full group-join between two sequences.

Declaration

public static IEnumerable<TResult> FullGroupJoin<TFirst, TSecond, TKey, TResult>(this IEnumerable<TFirst> first, IEnumerable<TSecond> second, Func<TFirst, TKey> firstKeySelector, Func<TSecond, TKey> secondKeySelector, Func<TKey, IEnumerable<TFirst>, IEnumerable<TSecond>, TResult> resultSelector, IEqualityComparer<TKey>? comparer)

Parameters

Type	Name	Description
IEnumerable<TFirst>	first	First sequence
IEnumerable<TSecond>	second	Second sequence
Func<TFirst, TKey>	firstKeySelector	The mapping from first sequence to key
Func<TSecond, TKey>	secondKeySelector	The mapping from second sequence to key
Func<TKey, IEnumerable<TFirst>, IEnumerable<TSecond>, TResult>	resultSelector	Function to apply to each pair of elements plus the key
IEqualityComparer<TKey>	comparer	The equality comparer to use to determine whether or not keys are equal. If null, the default equality comparer for TKey is used.

Returns

Type	Description
IEnumerable<TResult>	A sequence of elements joined from first and second.

Type Parameters

Name	Description
TFirst	The type of the elements in the first input sequence
TSecond	The type of the elements in the second input sequence
TKey	The type of the key to use to join
TResult	The type of the elements of the resulting sequence

Remarks

This operator uses deferred execution and streams the results. The results are yielded in the order of the elements found in the first sequence followed by those found only in the second. In addition, the callback responsible for projecting the results is supplied with sequences which preserve their source order.

Examples

The following code example demonstrates how to execute a full group join using FullGroupJoin

var people = new Person[]
{
    new("John Doe", 1),
    new("Jane Doe", 1),
    new("Lucy Ricardo", 2),
    new("Ricky Ricardo", 2),
    new("Fred Mertz", 3),
    new("Ethel Mertz", 3),
};

var pets = new Pet[]
{
    new("Bear", 103),
    new("Polly", 102),
    new("Minnie", 102),
    new("Mittens", 101),
    new("Patches", 101),
    new("Paws", 101),
};

var results = people
    .FullGroupJoin(
        pets,
        p => p.FamilyId,
        p => p.FamilyId,
        (familyId, familyPeople, familyPets) =>
        {
            var str1 = string.Join(", ", familyPeople.Select(p => p.Name));
            var str2 = string.Join(", ", familyPets.Select(p => p.Name));
            return $"({familyId}, [{str1}], [{str2}])";
        },
        new IntBy100Comparer());

foreach (var str in results)
    Console.WriteLine(str);

// This code produces the following output:
// (1, [John Doe, Jane Doe], [Mittens, Patches, Paws])
// (2, [Lucy Ricardo, Ricky Ricardo], [Polly, Minnie])
// (3, [Fred Mertz, Ethel Mertz], [Bear])

record Person(string Name, int FamilyId);
record Pet(string Name, int FamilyId);

class IntBy100Comparer : IEqualityComparer<int>
{
    public bool Equals(int x, int y) =>
        x % 100 == y % 100;

    public int GetHashCode(int obj) =>
        (obj % 100).GetHashCode();
}

Exceptions

Type	Condition
ArgumentNullException	first, second, firstKeySelector, secondKeySelector, or resultSelector is null.