move all zeros to the right in a matrix

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?

Answer 1

[Jan]

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)

Answer 2

[Matt J]

A=[1,2,3,0;0,0,0,1;8,0,9,0;4,3,2,1]

[m,n]=size(A); 

for i=1:m, 
  tmp=nonzeros(A(i,:)); 
  A(i,:)=[tmp.', zeros(1,n-numel(tmp))]; 
end

A,

Answer 3

[Jos (10584)]

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.'

Answer 4

[Andrei Bobrov]

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));