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CombinatoricsSubsetsT Method (ISetT, Int32, Boolean)

Generates all possibles subsets of size k of the given set.

Namespace:  Accord.Math
Assembly:  Accord.Math (in Accord.Math.dll) Version: 3.6.0
Syntax
public static IEnumerable<SortedSet<T>> Subsets<T>(
	this ISet<T> set,
	int k,
	bool inPlace = false
)
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Parameters

set
Type: System.Collections.GenericISetT
k
Type: SystemInt32
inPlace (Optional)
Type: SystemBoolean

Type Parameters

T

Return Value

Type: IEnumerableSortedSetT

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type ISetT. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
Examples
// Let's say we would like to compute all the
// subsets of size 2 of the set { 1, 2, 3, 4 }:
// 
ISet<int> set = new HashSet<int> { 1, 2, 3, 4 };

// The number of possible subsets might be too large
// to fit on memory. For this reason, we can compute
// values on-the-fly using foreach:

foreach (SortedSet<int> subset in Combinatorics.Subsets(set, k: 2))
{
    // ...
}

// Or we could try to compute them all and store in an array:
SortedSet<int>[] subsets = Combinatorics.Subsets(set, k: 2).ToArray();

// In either case, the result will be:

int[][] expected =
{
   new [] { 1, 2 },
   new [] { 1, 3 },
   new [] { 2, 3 },
   new [] { 1, 4 },
   new [] { 2, 4 },
   new [] { 3, 4 },
};
See Also