- looping through your array (from end to beginning) and remove all rotations (use circshift)
- design your own implementation of perms that avoids rotations
All possible permutation of a given vector.
6 views (last 30 days)
Show older comments
Given a vector, e.g [1 2 3 4 1], I would like to obtain all the possible permutations with NO REPETITION and NO ROTATION.
With
v = [1 2 3 4 1];
P = unique(perms(v),'rows');
I can avoid repetition but no rotation.
With rotation I mean that [1 2 1 4 3] and [2 1 4 3 1] are the same vector because the sequence is the same, just view from a different initial position.
I would like to be able to obtain all the possible combinations that avoid also this fact (rotation).
Thanks
1 Comment
Rik
on 23 Jul 2019
I suspect there are two options:
Neither is likely to be fast, and the first will also require the generation of a very large array for slightly larger vectors.
Accepted Answer
Stephen23
on 23 Jul 2019
Edited: Stephen23
on 23 Jul 2019
V = [1,2,3,4,1];
N = numel(V);
% Permutations:
P = perms(V(2:N));
P(:,N) = V(1);
P = unique(P,'rows')
% Rotations:
R = P; % just to allow comparison.
X = hankel(2:N,[N,1:N-1]);
for k = size(R,1):-1:1
T = R(k,:);
if any(ismember(T(X),R,'rows'))
R(k,:) = [];
end
end
Giving a 12x5 matrix:
R =
1 2 3 4 1
1 2 4 3 1
1 3 2 4 1
1 3 4 2 1
1 4 2 3 1
1 4 3 2 1
2 1 3 4 1
2 1 4 3 1
2 3 1 4 1
2 4 1 3 1
3 1 4 2 1
3 2 1 4 1
See also:
More Answers (0)
See Also
Categories
Find more on Dates and Time in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!