sort a matrix without using sort function

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John 2013-1-22

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评论： Jan 2017-10-2

how can I sort this matrix in descend order(only columns) without using sort function (my homework). for example: A= [

           17  24  1  8   15
           23  5   7  14  16
           4   6  13  20  22
           10  12 19  21  3
           11  18 25  2   9  ]

       B=[
           24   17  15  8   1
           23  16  14  7   5
           22  20  13  6   4
            . . . . . .. . . 
           .. .. . .. . .. .  ]

thanks

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John 2013-1-22

thanks for your help ,I was able to get this script work. thank your very much.

Cedric 2013-1-22

+1 for the "homework" tag! If other students were as honest as that, they would get more of my time ;-)

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回答（1 个）

Jan 2013-1-22

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/59559-sort-a-matrix-without-using-sort-function#answer_72044

编辑：Jan 2017-10-1

在 MATLAB Online 中打开

Here a solution, which I would not submit except with a bold explanation:

B = zeros(size(A));
n = size(A, 2);
for iRow = 1:size(A, 1)
  v = A(iRow, :);
  while any(diff(v) > 0)    % Test if sorted in descending order
    v = v(randperm(n, n));  % If not, shuffle the elements randomly
  end
  B(iRow, :) = v;
end

This is based on the "infinite monkey" theorem: Even a randomly typing monkey will find the solution by accident. In consequence is not guaranteed to finish until your homework is due.

[EDITED] This is not a serious suggestion. If you deliver this as solution of a homework, you might get an extra point for a nerdy kind of humor, perhaps. Ask an internet search engine for better sorting algorithms.

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Pame 2017-10-2

I like the insertion sort method, and i've got it to work for arrays, but not for matrixes.

Also currently trying to make a function which sorts matrixes in ascending order so that the lowest value element is in (1,1) and the highest value element is in the last row, last column.