How to keep count of occurence of column combination using 'for' loop?

Iam having matrix with large number of rows and column, I want to check the occurence of pair column cobminations (here for eg: I have taken 2 column) and based on that occurence I want to write every multiple of 2 count (mean to say: count 2,4,6... rows ) data into file .

Code I tried is:

Eg: A = [1,1;2,1;3,1;1,2;2,2;3,2;1,3;2,3;3,3;1,1;2,1;3,1;1,2;2,2;3,2;1,3;2,3;3,3;1,1;2,1;3,1;1,2;2,2;3,2;1,3;2,3;3,3;1,1;2,1;3,1]

b = unique(A,'rows'); % b = [1,1; 2,1; 3,1; 1,2; 2,2; 3,2; 1,3; 2,3; 3,3]

for k = 1:size(A(:,1))

count = (sum(A(:,1)==b) & sum(A(:,2)==b) % this is wrong but not able to figure it out how to write the logic.

if mod(count,2)==0

disp(count);

% writing data to file

end

end

May be solution is easy , since iam new to matlab iam not able to figure it out.

Thanks in advance.

[Adam Danz]

What does this part mean, "based on that occurence I want to write every multiple of 2 count..." ?

[Chaithra D]

mean to say that, For eg :consider (1,1) combination. (1,1) is occured 4 times in 'A' . I want to extract all column data of rows in which (1,1) combination ocurence count is detcted as 2nd and 4th occurnce .

[Adam Danz]

Still fuzzy to me.

Given your example input variable A, what's the expected output?

[Chaithra D]

Okay fine..

how to check the number of occurence count of pair(1,1) in matrix 'A'?

Answer 1

[Adam Danz]

How to check the number of occurence of pairs in the nx2 matrix A.

A = [1,1;2,1;3,1;1,2;2,2;3,2;1,3;2,3;3,3;1,1;2,1;3,1;1,2;2,2;3,2;1,3;2,3;3,3;1,1;2,1;3,1;1,2;2,2;3,2;1,3;2,3;3,3;1,1;2,1;3,1];
[unqPairs, ~, pairID] = unique(A,'rows','stable');
pairCount = histcounts(pairID,'BinMethod','integers');
T = table(unqPairs, pairCount(:), 'VariableNames', {'UniquePairs','Count'});

Result

  9×2 table
    UniquePairs    Count
    ___________    _____
      1    1         4  
      2    1         4  
      3    1         4  
      1    2         3  
      2    2         3  
      3    2         3  
      1    3         3  
      2    3         3  
      3    3         3