CODEWITHSUNDEEP
matlabfindunique
quinette
quinette

Reputation: 31

find out unrepetitive, unique data pair in matlab

I have a set of data looks like this:

data =

4 35
4 36
4 37
4 39
4 50
6 24
6 35
6 36
6 39
6 50
6 78
10 24
10 35
10 36
10 39
...

The actual matrix is in the order of 70000 X 2. What I want is to form a matrix containing all the unique data pair, so each element is not the same as the previous ones, would be look like

result =

4 35
6 24
10 36

I am think about a method like this
Step 1. find out all the index of unique column 1, in this case would be

index =

1
6
12

Step 2. Do a for-loop like this 

result = data(index);

for j = 1:length(index)

  if result(j,2) == result(j-1,2)

     result(j) = data(index+1)

  end

end

Here comes a problem, I have the possibility of getting some result like this

4 35
6 24
10 35

Then it is not unique. However, I don't want to write something like

 if result(j,2) = result(j-1,2) ...
     or result(j,2) = result(j-2,2) ...
     or result(j,2) = result(j-3,2) ...
     or result(j,2) = result(j-4,2) ...
 result(j) = data(index+?)

that would be even more complicated.

Thank you very much for the help in advance.

Upvotes: 3

Views: 4151

Answers (3)

quinette
quinette

Reputation: 31

Hey I just figure out how to do it :) Thank you all for help :) 

for j = 1:500 % random number, big enough to find out all my pairs
    k = 1;
    while any(bsxfun(@eq, store, data(k,2))|bsxfun(@eq, store, data(k,1)))
        k = k+1;
       if k > length(data)-1, break, end  

end

    pair(j,:) = data(k,:);
    store(2*j-1) = pair(j,1);
    store(2*j) = pair(j,2);
    fprintf('the loop we are at is %d \n',j);

end

Upvotes: 0

Mohsen Nosratinia
Mohsen Nosratinia

Reputation: 9864

This should work

I = true(size(data,1),1);
idx = [];
while any(I)
    idx(end+1) = find(I,1,'first');  %#ok
    I = I & all(~bsxfun(@eq, data, data(idx(end),:)),2);
end

result = data(idx,:);

Upvotes: 0

Lucius II.
Lucius II.

Reputation: 1832

try this:

unique(data,'rows')

C = unique(A,'rows') treats each row of A as a single entity and returns the unique rows of A. The rows of the matrix C are in sorted order. The 'rows' option does not support cell arrays.

Upvotes: 6

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