find the repetition of matrix rows

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yousef Yousef 2014-5-7

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https://ww2.mathworks.cn/matlabcentral/answers/128818-find-the-repetition-of-matrix-rows

编辑： Image Analyst 2014-5-9

I want to find out if the row i of mxn matrix is repeated ,the code should give logic 1.Otherwise zero"there are many ways but Im searching for the best one" Thanks

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Cedric 2014-5-7

Please provide an example.

José-Luis 2014-5-7

And please instead of asking an almost repeated question, try to explain better what you want, and please show some effort before asking for a ready-made answer.

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Answer 1

Roberto 2014-5-9

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编辑：Roberto 2014-5-9

在 MATLAB Online 中打开

a = [1 2 3; 4 5 6;1 2 3; 3 2 4; 1 2 3; 3 2 1; 1 3 2] ;
row2check = 1;
repeated = 0 ;
for i = 1 : size(a,1)    
  repeated = repeated + prod(double([a(row2check,:)== a(i,:)])) ;
end
fprintf('\n Row number %i is reapeated %i times in matrix!\n\n',row2check,repeated);

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Answer 2

Image Analyst 2014-5-9

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编辑：Image Analyst 2014-5-9

在 MATLAB Online 中打开

Using ismember() is the usual method. Try this:

m = randi(9, [5000, 3]); % Create sample data.
% For demo, let's make sure row 9 is a repeat.
% In other words, row 9 is a duplicate of row 1. 
m(9,:) = m(1,:); 
% Let's see if row i is repeated
i = 1; % Could be any number up to size(m, 1);
% Use ismember to find repeated rows.
[lia, locb] = ismember(m, m(i,:), 'rows');
% locb is a logival vector.  Find the actual row numbers.
repeatedRows = find(locb)