# sorting according to another vector

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Danielle Leblanc am 5 Aug. 2011
Kommentiert: Walter Roberson am 10 Feb. 2022
Hi,
I have a vector A that doesn't follow any order. I want to sort Matrix B that has the first column of values similar to those of A but in different order. Is it possible to sort B according to A using a single function or should I write many codes to do so?
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### Akzeptierte Antwort

Walter Roberson am 5 Aug. 2011
Sorry you will have to use multiple calls:
[a_sorted, a_order] = sort(A);
newB = B(a_order,:);
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Jan am 5 Aug. 2011
@Danielle: Ok, then I have misunderstood your question. The information that B has "value similar to those of A" is meaningless then - correct?

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### Weitere Antworten (4)

Jan am 5 Aug. 2011
I'm not sure, if I understand the question correctly. Do you want to bring B in the same order as the unsorted A? Then either sort both vectors and mix their sorting indicies:
[As, Ai] = sort(A);
[Bs, Bi] = sort(B(:, 1));
ABi(Ai) = Bi;
Now ABi is the sorting index to bring B to the order of A:
isequal(A, B(ABi, 1)) % ==> 1
Or let ISMEMBER do this for you:
[dummy, order] = ismember(A, B(:, 1));
isequal(A, B(order, 1)) % ==> 1
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Pramit Biswas am 31 Jan. 2018
Bearbeitet: Pramit Biswas am 31 Jan. 2018
function B = sortBlikeA(A,B)
[~, Ao] = sort(A);
Bs=sort(B);
B(Ao)=Bs;
end
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Marco Schnizer am 10 Feb. 2022
Nice Code, thank you!

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inzamam shoukat am 26 Okt. 2018
Bearbeitet: inzamam shoukat am 26 Okt. 2018
Hi every one......i have matrix lets suppose [3 2;1 9]
what i want to do is sort out the only first column in ascending order but problem is how to do it so that corresponding values which is in first row 2 for 3 in second row 9 for 1 change their positions according to the position of values of first column being sorted i.e [1 9; 3 2]...
LIMITATION : sorting operation never applied to second column....
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Steven Lord am 26 Okt. 2018
Use sortrows.

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Marco Bertola am 14 Feb. 2021
Bearbeitet: Marco Bertola am 14 Feb. 2021
I think the question (which I had too) was:
I have a reference vector [1.2 3.3 4.4] eg
and another ``similar'' vector [3.2 1.1 4.4]
Problem; find the optimal sorting of vector 2 so that it is ''closest'' (L^2 norm eg) to the reference vector.
Say X is your reference vector of size (1,n) and Xnew is the new vector of the same size
then what you want is accomplished like so:
dist = abs(ones(n,1)*X - Xnew.' ones(1,n));
[t1,J]= min(dist);
%now J has the optimal permutation%
Xnew=Xnew[J]
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Walter Roberson am 10 Feb. 2022
If you are not permitted to duplicate any elements, and the entries are all finite then
[~, refidx] = sort(reference_vector);
sorted_similar = sort(similar_vector);
new_similar = sorted_similar(refidx);

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