Reveresing the order of columns in an array
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Hi guys,
I would like to write a code to reverse the columns order as in a following example:
q=[1 2 3 4, 5 6 7 8, 9 10 11 12, 13 14 15 16, 17 18 19 20];
for example, the program randomly picks:
i1=2
i2=4
so we want to rearrange the order of colums from the second till the forth one and as an output get
qnew=[1 4 3 2, 5 8 7 6, 9 12 11 10, 13 16 15 14, 17 20 19 18]
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Réponses (3)
Les Beckham
le 17 Mai 2022
Modifié(e) : Les Beckham
le 17 Mai 2022
% Note: use semicolons instead of commas for row breaks so you get 4 columns
q = [1 2 3 4; 5 6 7 8; 9 10 11 12; 13 14 15 16; 17 18 19 20]
i1=2;
i2=4;
qnew = q;
qnew(:,i1) = q(:,i2);
qnew(:,i2) = q(:,i1);
disp(qnew)
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Bartosz Bagrowski
le 17 Mai 2022
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Les Beckham
le 17 Mai 2022
Well, that is a different question. This q only has two columns. It appears that now you want to swap the rows.
q=[1 2; 3 4; 5 6; 7 8; 9 10; 11 12]
i1=2;
i2=6;
qnew = q;
qnew(i1,:) = q(i2,:);
qnew(i2,:) = q(i1,:);
disp(qnew)
Torsten
le 17 Mai 2022
A = [1 2; 3 4; 5 6; 7 8; 9 10; 11 12];
perm = [1 6 5 4 3 2];
A = A(perm,:)
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