CODEWITHSUNDEEP
matlab
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Reputation: 2299

How to select only certain rows in a matrix in Matlab?

I have a matrix A in Matlab 

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

where the last column contains natural indices possibly repeated. For each index in the last column, I want to select the first row of A associated with that index and create the matrix 

B=[1 2 3 |1;
   2 3 4 |2;
   6 7 0 |3;
   6 5 4 |4]

Upvotes: 2

Views: 241

Answers (1)

Dan
Dan

Reputation: 45752

Use unique to get the values and indices you require:

[U,I] = unique(A(:,4), 'first')

Then 

A(I,:)

Upvotes: 5

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