loop a matrix through disorder columns indices

Question

Yousuf Khan 2022-7-31

0
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https://ww2.mathworks.cn/matlabcentral/answers/1771480-loop-a-matrix-through-disorder-columns-indices

回答： Abderrahim. B 2022-7-31

I have a matrix A which has 100 rows and 5 columns, I would like to iterate the matrix with disorder indices of columns and save them in each iteration, column indices [2;5;3;4;1]. 1st iteration: get all the rows of A with column 2 then do some processes. 2nd iteration : get all the rows of A with columns 2 and 5. ..... last iteration: get all the rows and columns of A. Anyone helps me to implement it on Matlab environment please.

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Answer 1

Abderrahim. B 2022-7-31

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1771480-loop-a-matrix-through-disorder-columns-indices#answer_1018610

在 MATLAB Online 中打开

Hi!

What about this below!

% Dummy A
A = randi(4, 100, 5 )  ;
% 
B = [] ;
for cIdx = [2 5 3 4 1]
    
 B = [B, A(:, cIdx )]
end
B = 100×1
     3
     3
     3
     4
     1
     4
     1
     2
     1
     4
B = 100×2
     3     2
     3     3
     3     3
     4     4
     1     1
     4     3
     1     4
     2     1
     1     3
     4     3
B = 100×3
     3     2     2
     3     3     1
     3     3     3
     4     4     1
     1     1     1
     4     3     3
     1     4     4
     2     1     1
     1     3     2
     4     3     2
B = 100×4
     3     2     2     1
     3     3     1     2
     3     3     3     4
     4     4     1     2
     1     1     1     2
     4     3     3     2
     1     4     4     2
     2     1     1     2
     1     3     2     2
     4     3     2     3
B = 100×5
     3     2     2     1     4
     3     3     1     2     1
     3     3     3     4     2
     4     4     1     2     1
     1     1     1     2     4
     4     3     3     2     4
     1     4     4     2     3
     2     1     1     2     4
     1     3     2     2     2
     4     3     2     3     2