How to order a matrix?
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Hello,
I have a matrix,
A=[ 100 5 0 ; 200 0 -5 ; 300 0 0 ; 300 5 0 ; -100 0 5 ; 300 0 0; 300 0 5];
I want to get,
A= [100 5 0; 200 0 -5 ; 300 0 0; 300 5 0 ; 300 0 5 ; -100 0 5];
I am writing code:
B= unique(A(:, 2:3),'rows');
then it's removing the first row as 5 0 is also repeted for the 4th row 300 5 0 but I need to keep the 1st row.
Is it possible to do?
4 Kommentare
Adam
am 23 Apr. 2019
It's not really obvious from your example what you are trying to achieve in a more general case. Your example just removes one row (which can be removed by using just a simple unique as mentioned) and then orders the remaining ones in a fairly unintuitive manner with respect to how they started.
What are you actually trying to keep? If you are trying to keep all unique rows then what I wrote works fine, if you are really trying to only run a unique on the 2nd and 3rd columns then your version does that, but from what you say, that isn't what you want to do.
Antworten (2)
Alex Mcaulley
am 23 Apr. 2019
Bearbeitet: Alex Mcaulley
am 23 Apr. 2019
Try this:
[~,ia,~] = unique(A(:, 2:3),'rows','stable');
B = A(ia,:);
7 Kommentare
Alex Mcaulley
am 23 Apr. 2019
Using round
If you want to round the first column:
A = [ 100 5 0 ; 200 0 -5 ; 300 0 0 ; 300 5 0 ; -100 0 5 ; 300 0 0; 300 0 5];
A(:,1) = round(A(:,1),-2);
[~,ia,~] = unique(A(:, 2:3),'rows','stable');
B = A(ia,:);
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