Sorting specific rows with a specific column
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I would like to sort first 3 rows of a matrix A with column 2 and then next 3 rows without changing the first three rows again with column 2. eg, A = [1 6 50; 5 2 50; 7 1 50; 2 5 53; 5 1 53; 7 3 53] Later, with same logic, I would like to sort a matrix with 100 rows.
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Jan
on 30 Jun 2017
Edited: Jan
on 30 Jun 2017
The question is not clear. What does "sort with column 2" mean? A guess:
A = [1 6 50; 5 2 50; 7 1 50; 2 5 53; 5 1 53; 7 3 53];
for k = 1:3:size(A, 1)
[dummy, index] = sort(A(k:k+2, 2));
A(k:k+2, :) = A(index + k - 1, :);
end
Please check if this produces the wanted output. If so, explain, if you need more speed.
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Jan
on 30 Jun 2017
I think the best web source for such questions is: https://www.mathworks.com/matlabcentral/answers/ :-)
After reading the Getting Started chapters of the documentation and seeing Matlab's Onramp, it helps do discuss such questions in the forum until you get familar with creating efficient algorithms. See also: https://www.mathworks.com/matlabcentral/answers/8026-best-way-s-to-master-matlab
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