Switch columns in a matrix without a loop
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How can I switch specific columns in a matrix (for example every 4th column), in one command without using a loop? Is it even possible?
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Florian
le 13 Avr 2013
Hi Yakov,
please specify, since in a matrix with 10 columns you will have for 3 columns at index 3,6,9 but only 2 columns with index mod 5, namely 5, 10.
Hence could you please specify exactly which columns you want to switch. Or do you want to mix all columns randomly?
Regards, Florian
Ahmed A. Selman
le 13 Avr 2013
for exchanging two columns 3 - 9 :
A = randi(20,4,10); % A random 4 by 10 matrix of integers
A(1,:)=[1 2 3 4 5 6 7 8 9 10]; % the first row only is replaced for clarity
B=A; % the new matrix, same as A for now
B(:,3)=A(:,9); % puts 3 of B with 9 of A
B(:,9)=A(:,3); % puts 9 B with 3 A
B has columns 3 and 9 exchanged with A 9 and 3, and A is intact. A similar method to exchange columns 3 - 6 - 9 - 3. So if you want to use same A, use A=B.
To exchange rows use B(row_no,:)=A(new_row,:)..etc
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