MATLAB Answers

# Calculate the remaining index of my data

5 views (last 30 days)
muhammad ismat on 27 Sep 2017
Commented: muhammad ismat on 28 Sep 2017
If i have
x= 1 2
3 4
2 5
1 5
is the index of my data. i want to get on remaining of these index but not need index that have i=j i.e [ (1 1) (2 2) (3 3)(4 4)(5 5) and not need fliplr of x i.e [(2 1)(4 3)(5 2)(5 1)]. so i want to the result
result=
1 3
1 4
2 3
2 4
3 5
4 5
that should not contain fliplr of any index.
##### 1 CommentShowHide None
Rik on 27 Sep 2017
It is not clear what your question is. It sounds like you could solve your problem with logical indexing, or even find (and maybe a call to ismember(fliplr(A),A)), but without understanding your problem better I can't help you with actual code.

Sign in to comment.

### Accepted Answer

the cyclist on 27 Sep 2017
Here is one way.
x= [1 2
3 4
2 5
1 5];
result = zeros(5*2,2);
ri = 1;
for ii=1:5
for jj = ii+1:5
result(ri,:) = [ii jj];
ri = ri+1;
end
end
isRowToRemove = ismember(result,x,'rows');
result(isRowToRemove,:) = [];
There is certainly a better way to pre-populate the array result with all possible row values than using the loops, but I got lazy.
##### 1 CommentShowHide None
muhammad ismat on 28 Sep 2017
Thank you very much,the cyclist

Sign in to comment.

### More Answers (1)

OCDER on 27 Sep 2017
%Getting index of an arbitrary matrix
[x, y] = find(ones(5, 'logical'));
x = [x y];
%Remove index i == j
x(x(:,1) == x(:,2), :) = [];
%Get unique x,y and not those that are y,x
x = unique(sort(x, 2), 'rows');
x =
1 2
1 3
1 4
1 5
2 3
2 4
2 5
3 4
3 5
4 5
##### 0 CommentsShowHide -1 older comments

Sign in to comment.

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!