MATLAB: Reorder label

Question

Andrei,

Thank you very much for your answer but when I put it the new made L4 introduces a row with 0 between every rows. How can I eliminate this rows? And if the matrix change of size, Have I that change anythings?

L9 =

     1     1     0     0
     5     5     0     0
     0     5     7     7
     0     0     9    11

Lp = zeros(size(L9).*[2 1]); Lp(1:2:end) = L9; Lp = bwlabel(Lp')'; L9(L9~=0)=Lp(Lp~=0); Lp =

     1     1     0     0
     0     0     0     0
     2     2     0     0
     0     0     0     0
     0     3     3     3
     0     0     0     0
     0     0     4     4
     0     0     0     0

Answer 1

L4 = zeros(size(L9).*[2 1]);
L4(1:2:end) = L9;
L4 = bwlabel(L4')';
Lp = L4(any(L4,2),:);