move all zeros to the right in a matrix
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I have a matrix like
[1,2,3,0;
0,0,0,1;
8,0,9,0;
4,3,2,1]
and I need to move all zeros to the right, and other numbers to the left. like:
[1,2,3,0;
1,0,0,0;
8,9,0,0;
4,3,2,1]
how can I do this?
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Answers (4)
Jan
on 14 Feb 2018
Edited: Jan
on 14 Feb 2018
X = [1,2,3,0; 0,0,0,1; 8,0,9,0; 4,3,2,1];
[c, r] = size(X);
[~, S] = sort(X == 0, 2);
Index = sub2ind(size(X), repmat((1:c).', 1, r), S);
Y = X(Index)
Or replace sub2in by a simpler method:
c = size(X, 1);
[~, S] = sort(X == 0, 2);
Y = X((1:c).' + (S - 1) * c) % >= R2016b: Auto-expanding
With older Matlab versions:
Y = X(bsxfun(@plus, (1:c).', (S - 1) * c)
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Jos (10584)
on 14 Feb 2018
Edited: Jos (10584)
on 14 Feb 2018
Here is one way:
% data
X = [1 2 3 0 4 ; 1 0 0 0 2 ; 1 0 2 3 4 ; 1 2 3 0 0 ; 0 0 0 0 1]
% engine
X = X.'
Y = zeros(size(X))
Q = logical(X)
Qs = sort(Q,1,'descend')
Y(Qs) = X(Q)
Y = Y.'
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Andrei Bobrov
on 14 Feb 2018
Edited: Andrei Bobrov
on 14 Feb 2018
a = [1,2,3,0;
0,0,0,1;
8,0,9,0;
4,3,2,1];
b = a';
out = sort(b,'descend')
out(out>0) = b(b>0);
out = out';
or
a = [1,2,3,0;
0,0,0,1;
8,0,9,0;
4,3,2,1];
lo = a ~= 0;
[ii,~,k] = find(cumsum(lo,2).*lo);
out = accumarray([ii,k],a(lo));
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