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How to arrange rows of a matrix to get a specific column in order?

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Mr M.
Mr M. 2015-2-25
评论： RAGHAVENDRA 2015-2-26
are there any built-in function for this, or I have to extract that column, order it, and arrange the matrix separately?
  1 个评论
RAGHAVENDRA
RAGHAVENDRA 2015-2-25
编辑：Guillaume 2015-2-25
You can do the following way:
let us say i want to sort X according to 5th column, then:
X=randi(5,[10 10]);% 10X10 random matrix with elements <= 5
[S,I]=sort(X(:,5),'ascend');
Y=X(I,:);

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回答（2 个）

Jos (10584)
Jos (10584) 2015-2-25
编辑：Jos (10584) 2015-2-25
Yes, there is! Take a look at SORTROWS
M = [1 2 3 ; 2 3 1 ; 3 1 2]
sortrows(M,2)
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Jos (10584)
Jos (10584) 2015-2-25
Oh, I misunderstood. You only want to sort column 3, leaving the other columns as they are?
M(:,3) = sort(M(:,3))
Guillaume
Guillaume 2015-2-25
Jos, you didn't misunderstand the question and your answer was actually correct. Raghavendra should actually have tested the posted code, which sorted the rows according to the second column.
To be very clear:
sortrows(M, cols)
sorts the rows of M according the columns defined in cols, so
sortrows(M, 3)
sorts the rows of M so that values in column 3 are ascending
sortrow(M, [3 -2])
sort the rows of M, first according to column 3 in ascending order. For identical values in column 3 it then uses column 2 in descending order.
It's all explained in the doc.

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RAGHAVENDRA
RAGHAVENDRA 2015-2-25
You can do the following way:
let us say i want to sort X according to 5th column, then:
X=randi(5,[10 10]);% 10X10 random matrix with elements <= 5
[S,I]=sort(X(:,5),'ascend');
Y=X(I,:);
  3 个评论
显示 1更早的评论
Guillaume
Guillaume 2015-2-25
Raghavendra, as mentioned in another of your answer, please use the code formatting tool when you answer, so that it is easily readable.
It's not that hard, just add two spaces before writing the line of code, or select the code and click the {} Code button.
People answering questions should know how to use the forum tools.

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