Removing repeated numbers in a matrix

Ex: In a matrix

A = [9 9 1 1 2 2 2 2 2 0 3 3; 7 7 4 4 4 5 5 6 6 6 6 6 ; 8 8 7 7 7 8 8 8 9 9 9 5]

, i want to eliminate all repeating elements and retain non-repeating elements

i.e. from the above example

A = [9 1 2 0 3 ; 7 4 5 6 ; 8 7 8 9 5]

To prevent a dimensions error because of different output results, the remaining entries on the left can be filled by zero like here

A = [9 1 2 0 3 ; 7 4 5 6 0 ; 8 7 8 9 5]

Answer 1

[Stephen23]

>> A = [9,9,1,1,2,2,2,2,2,0,3,3;7,7,4,4,4,5,5,6,6,6,6,6;8,8,7,7,7,8,8,8,9,9,9,5]
A =
   9   9   1   1   2   2   2   2   2   0   3   3
   7   7   4   4   4   5   5   6   6   6   6   6
   8   8   7   7   7   8   8   8   9   9   9   5
>> X = diff(A(:,[1,1:end]),1,2)~=0;
>> X(:,1) = true;
>> S = size(A);
>> [R,~] = ndgrid(1:S(1),1:S(2));
>> C = cumsum(+X,2);

Method one: accumarray:

>> B = accumarray([R(:),C(:)],A(:),[],@mode,0)
B =
   9   1   2   0   3
   7   4   5   6   0
   8   7   8   9   5

Method two: indexing:

>> B = zeros(S(1),max(C(:)));
>> B(sub2ind(S,R,C)) = A
B =
   9   1   2   0   3
   7   4   5   6   0
   8   7   8   9   5

Answer 2

[KSSV]

A = [9 9 1 1 2 2 2 2 2 0 3 3; 7 7 4 4 4 5 5 6 6 6 6 6 ; 8 8 7 7 7 8 8 8 9 9 9 5] ;
[m,n] = size(A) ; 
C = cell(m,1) ; 
for i = 1:m
  C{i} = unique(A(i,:)) ; 
end
L = cellfun(@length,C) ;
B = zeros(m,max(L)) ; 
for i = 1:m
  B(i,1:L(i)) = C{i} ; 
end

[Stephen23]

Note that this returns the sorted unique elements in each row:

>> B
B =
   0   1   2   3   9
   4   5   6   7   0
   5   7   8   9   0

which does not match what the question requested (compare against the example output).

[Bruno Luong]

Easy to fix with 'stable' option

A = [9 9 1 1 2 2 2 2 2 0 3 3;
    7 7 4 4 4 5 5 6 6 6 6 6 ;
    8 8 7 7 7 8 8 8 9 9 9 5]

c=arrayfun(@(r) unique(A(r,:),'stable'), 1:size(A,1), 'unif', 0);
n=max(cellfun(@length,c));
B=cell2mat(cellfun(@(x) [x,zeros(1,n-length(x))], c, 'unif', 0)')

[Stephen23]

"Easy to fix with 'stable' option"

Nope, not fixed. Lets try it:

>> c = arrayfun(@(r) unique(A(r,:),'stable'), 1:size(A,1), 'unif', 0);
>> n = max(cellfun(@length,c));
>> B = cell2mat(cellfun(@(x) [x,zeros(1,n-length(x))], c, 'unif', 0)')
B =
     9     1     2     0     3
     7     4     5     6     0
     8     7     9     5     0

Note that the last row differs from the expected output given in the original question:

     9     1     2     0     3
     7     4     5     6     0
     8     7     8     9     5

[Bruno Luong]

You are absolutely right.