How to get all unique posiblity's out of a list?

Question

For my problem I have a list of a count larger then 6+. From that list I would like to make a list containing every possible combination of the original cards that is exactly 6 cards long. (they have to be unique and order doesn't matter)

so object 01,02,03,04,05,06 is the same for me as 06,05,04,03,02,01

//STARTER list with more then 6 value's
List < ClassicCard > lowCardsToRemove = FrenchTarotUtil.checkCountLowCardForDiscardChien(handCards);

The solution i found and used:

public static List generateAllSubsetCombinations(object[] fullSet, ulong subsetSize) { if (fullSet == null) { throw new ArgumentException("Value cannot be null.", "fullSet"); } else if (subsetSize < 1) { throw new ArgumentException("Subset size must be 1 or greater.", "subsetSize"); } else if ((ulong)fullSet.LongLength < subsetSize) { throw new ArgumentException("Subset size cannot be greater than the total number of entries in the full set.", "subsetSize"); }

    // All possible subsets will be stored here
    List<object[]> allSubsets = new List<object[]>();

    // Initialize current pick; will always be the leftmost consecutive x where x is subset size
    ulong[] currentPick = new ulong[subsetSize];
    for (ulong i = 0; i < subsetSize; i++) {
        currentPick[i] = i;
    }

    while (true) {
        // Add this subset's values to list of all subsets based on current pick
        object[] subset = new object[subsetSize];
        for (ulong i = 0; i < subsetSize; i++) {
            subset[i] = fullSet[currentPick[i]];
        }
        allSubsets.Add(subset);

        if (currentPick[0] + subsetSize >= (ulong)fullSet.LongLength) {
            // Last pick must have been the final 3; end of subset generation
            break;
        }

        // Update current pick for next subset
        ulong shiftAfter = (ulong)currentPick.LongLength - 1;
        bool loop;
        do {
            loop = false;

            // Move current picker right
            currentPick[shiftAfter]++;

            // If we've gotten to the end of the full set, move left one picker
            if (currentPick[shiftAfter] > (ulong)fullSet.LongLength - (subsetSize - shiftAfter)) {
                if (shiftAfter > 0) {
                    shiftAfter--;
                    loop = true;
                }
            }
            else {
                // Update pickers to be consecutive
                for (ulong i = shiftAfter+1; i < (ulong)currentPick.LongLength; i++) {
                    currentPick[i] = currentPick[i-1] + 1;
                }
            }
        } while (loop);
    }

    return allSubsets;
}

See http://stackoverflow.com/questions/127704/algorithm-to-return-all-combinations-of-k-elements-from-n — M. Mennan Kara, Mar 30 '16 at 13:00
So you want to generate all the combinations of `k` values from `n` values? like `n` choose `k` or `nCk` in statistics? — Louie Almeda, Mar 30 '16 at 13:01
I want every unique combo of "k" objects from "n" values where lengt n is variable and where k lengt is alway's 6. — schadowfax, Mar 30 '16 at 13:13

score 0 · Answer 1 · answered Mar 30 '16 at 13:47

0

This one is not from me, but it does the job!

List <ClassicCard> lowCardsToRemove = FrenchTarotUtil.checkCountLowCardForDiscardChien(handCards);
var result = Combinator.Combinations(lowCardsToRemove, 6);

public static class Combinator
{
    public static IEnumerable<IEnumerable<T>> Combinations<T>(this IEnumerable<T> elements, int k)
    {
        return k == 0 ? new[] { new T[0] } :
          elements.SelectMany((e, i) =>
            elements.Skip(i + 1).Combinations(k - 1).Select(c => (new[] { e }).Concat(c)));
    }
}

answered Mar 30 '16 at 13:47

Florian-Rh

777
8
26

It is possible this would work but i didn't test it. Because i would love to do a check when i get a possible subset. But thanks for the input I found a solution and i post it undernet this for other people if they would look for something like this one day – schadowfax Mar 31 '16 at 08:37

How to get all unique posiblity's out of a list?

1 Answers1