MATLAB: While Loop Keep running non stop !!

counterduplicateforlooprepeatedreshapingswappingwhile

i have a matrix A
A=[  1     1     2
     3     3     4
     4     4     5
     5     5     6
     6     6     7
     7     7     8
     8     8     9
     9     9    10
    10    10    11
    12    12    13
    13    13    14
    15    15    16
    16    16    17
    17    17    18
    18     2    19
    19    19    20
    20    20    21
    21    21    22
    22     3    23
    23    23    24
    24    24    25
    26    26    27
    27    27    28
    28    28    29
    28    29    30
    30    30    31
    31    31    32
    33    21     8
    34     9    15
    35    22    12
    36    18    33
    37    25    29]
i want to make a loop which detect repeated values of column no. 3 then swap the repeated value of column 3 with column 2 from bottom to up and keep swapping going up until no repeated values in column 3
i made somthing like that
[c,ia,ib] = unique(A(:,3)); 
FF=length(ia)-1;
Ncount = histc(A(:,3), c);
    for i=FF:-1:1
 Ncount = histc(A(:,3), c);
 while Ncount(i)==2
A(i,[2,3])=A(i,[3,2]);
Ncount = histc(A(:,3), c);
 end
    end
but the loop keep running and i think that because of two Ncount=2 at row 28 (29 is repeated in row 37 and 28) and Ncount=2 at row 7 (8 is repeated at row 7 and 33) !!
please help !

Best Answer

Ok, I think I got something working. The while loop was a fine choice, it was more a matter of indexing and changing things together. Also, it was impossible to start changing values from the back, because you ran into an infinite loop.
[c,ia,ib] = unique(A(:,3));
Ncount = histc(A(:,3), c);
if sum(Ncount >= 2) >0;
    c2 = c(Ncount >= 2);
    while sum(Ncount >= 2) > 0
        A(find(ismember(A(:,3),c2),max(Ncount),'first'),[3,2]) = A(find(ismember(A(:,3),c2),max(Ncount),'first'),[2,3]);
        [c,ia,ib] = unique(A(:,3));
        Ncount = histc(A(:,3), c);
        c2 = c(Ncount >= 2);
    end
end
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