Method DenseRankBy

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

Ranks each item in the sequence in ascending order by a specified key using a default comparer, with no gaps in the ranking values. The rank starts at one and keeps incrementing by one for each different item.

Declaration

public static IEnumerable<(TSource item, int rank)> DenseRankBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)

Parameters

Type	Name	Description
IEnumerable<TSource>	source	The sequence of items to rank
Func<TSource, TKey>	keySelector	A key selector function which returns the value by which to rank items in the sequence

Returns

Type	Description
IEnumerable<(TSource item, int rank)>	A sorted sequence of items and their rank.

Type Parameters

Name	Description
TSource	The type of the elements in the source sequence
TKey	The type of the key used to rank items in the sequence

Remarks

This method is implemented by using deferred execution. However, source will be consumed in it's entirety immediately when first element of the returned sequence is consumed.

Examples

The following code example demonstrates how to rank the items in a sequence according to a key using DenseRankBy.

var sequence = new[]
{
    (key: 5, text: "1"),
    (key: 5, text: "2"),
    (key: 4, text: "3"),
    (key: 4, text: "4"),
    (key: 3, text: "5"),
    (key: 3, text: "6"),
    (key: 2, text: "7"),
    (key: 2, text: "8"),
    (key: 1, text: "9"),
    (key: 1, text: "10"),
};

// Get the top N sets of items
var result = sequence
    .DenseRankBy(
        x => x.key);

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

// This code produces the following output:
// [((1, 9), 1), ((1, 10), 1), ((2, 7), 2), ((2, 8), 2), ((3, 5), 3), ((3, 6), 3), ((4, 3), 4), ((4, 4), 4), ((5, 1), 5), ((5, 2), 5)]

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

DenseRankBy<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>, OrderByDirection)

Ranks each item in the sequence in the order defined by sortDirection by a specified key using a default comparer, with no gaps in the ranking values. The rank starts at one and keeps incrementing by one for each different item.

Declaration

public static IEnumerable<(TSource item, int rank)> DenseRankBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, OrderByDirection sortDirection)

Parameters

Type	Name	Description
IEnumerable<TSource>	source	The sequence of items to rank
Func<TSource, TKey>	keySelector	A key selector function which returns the value by which to rank items in the sequence
OrderByDirection	sortDirection	Defines the ordering direction for the sequence

Returns

Type	Description
IEnumerable<(TSource item, int rank)>	A sorted sequence of items and their rank.

Type Parameters

Name	Description
TSource	The type of the elements in the source sequence
TKey	The type of the key used to rank items in the sequence

Remarks

This method is implemented by using deferred execution. However, source will be consumed in it's entirety immediately when first element of the returned sequence is consumed.

Examples

The following code example demonstrates how to rank the items in a sequence according to a key using DenseRankBy.

var sequence = new[]
{
    (key: 5, text: "1"),
    (key: 5, text: "2"),
    (key: 4, text: "3"),
    (key: 4, text: "4"),
    (key: 3, text: "5"),
    (key: 3, text: "6"),
    (key: 2, text: "7"),
    (key: 2, text: "8"),
    (key: 1, text: "9"),
    (key: 1, text: "10"),
};

// Get the top N sets of items
var result = sequence
    .DenseRankBy(
        x => x.key,
        OrderByDirection.Ascending);

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

// This code produces the following output:
// [((1, 9), 1), ((1, 10), 1), ((2, 7), 2), ((2, 8), 2), ((3, 5), 3), ((3, 6), 3), ((4, 3), 4), ((4, 4), 4), ((5, 1), 5), ((5, 2), 5)]

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

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

Ranks each item in the sequence in ascending order by a specified key using a caller-supplied comparer, with no gaps in the ranking values. The rank starts at one and keeps incrementing by one for each different item.

Declaration

public static IEnumerable<(TSource item, int rank)> DenseRankBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, IComparer<TKey> comparer)

Parameters

Type	Name	Description
IEnumerable<TSource>	source	The sequence of items to rank
Func<TSource, TKey>	keySelector	A key selector function which returns the value by which to rank items in the sequence
IComparer<TKey>	comparer	An object that defines the comparison semantics for keys used to rank items

Returns

Type	Description
IEnumerable<(TSource item, int rank)>	A sorted sequence of items and their rank.

Type Parameters

Name	Description
TSource	The type of the elements in the source sequence
TKey	The type of the key used to rank items in the sequence

Remarks

This method is implemented by using deferred execution. However, source will be consumed in it's entirety immediately when first element of the returned sequence is consumed.

Examples

The following code example demonstrates how to rank the items in a sequence according to a key using DenseRankBy.

var sequence = new[]
{
    (key: 5, text: "1"),
    (key: 5, text: "2"),
    (key: 4, text: "3"),
    (key: 4, text: "4"),
    (key: 3, text: "5"),
    (key: 3, text: "6"),
    (key: 2, text: "7"),
    (key: 2, text: "8"),
    (key: 1, text: "9"),
    (key: 1, text: "10"),
};

// Get the top N sets of items
var result = sequence
    .DenseRankBy(
        x => x.key,
        Comparer<int>.Create((x, y) => (x % 2).CompareTo(y % 2)));

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

// This code produces the following output:
// [((4, 3), 1), ((4, 4), 1), ((2, 7), 1), ((2, 8), 1), ((5, 1), 2), ((5, 2), 2), ((3, 5), 2), ((3, 6), 2), ((1, 9), 2), ((1, 10), 2)]

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

DenseRankBy<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>, IComparer<TKey>, OrderByDirection)

Ranks each item in the sequence in the order defined by sortDirection by a specified key using a caller-supplied comparer, with no gaps in the ranking values. The rank starts at one and keeps incrementing by one for each different item.

Declaration

public static IEnumerable<(TSource item, int rank)> DenseRankBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, IComparer<TKey> comparer, OrderByDirection sortDirection)

Parameters

Type	Name	Description
IEnumerable<TSource>	source	The sequence of items to rank
Func<TSource, TKey>	keySelector	A key selector function which returns the value by which to rank items in the sequence
IComparer<TKey>	comparer	An object that defines the comparison semantics for keys used to rank items
OrderByDirection	sortDirection	Defines the ordering direction for the sequence

Returns

Type	Description
IEnumerable<(TSource item, int rank)>	A sorted sequence of items and their rank.

Type Parameters

Name	Description
TSource	The type of the elements in the source sequence
TKey	The type of the key used to rank items in the sequence

Remarks

This method is implemented by using deferred execution. However, source will be consumed in it's entirety immediately when first element of the returned sequence is consumed.

Examples

The following code example demonstrates how to rank the items in a sequence according to a key using DenseRankBy.

var sequence = new[]
{
    (key: 5, text: "1"),
    (key: 5, text: "2"),
    (key: 4, text: "3"),
    (key: 4, text: "4"),
    (key: 3, text: "5"),
    (key: 3, text: "6"),
    (key: 2, text: "7"),
    (key: 2, text: "8"),
    (key: 1, text: "9"),
    (key: 1, text: "10"),
};

// Get the top N sets of items
var result = sequence
    .DenseRankBy(
        x => x.key,
        Comparer<int>.Create((x, y) => (x % 2).CompareTo(y % 2)),
        OrderByDirection.Ascending);

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

// This code produces the following output:
// [((4, 3), 1), ((4, 4), 1), ((2, 7), 1), ((2, 8), 1), ((5, 1), 2), ((5, 2), 2), ((3, 5), 2), ((3, 6), 2), ((1, 9), 2), ((1, 10), 2)]

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.