MATLAB: How to sort a matrix so that sorting a column will make changes to corresponding other columns?

matrixmatrix manipulationsort

Lets say that my matrix is

[ x3   y3
  x1   y1
  x2   y2]

I want to sort the second column y in ascending order so that the respective 1'st column is also sorted accordingly. I want the output to be like this:

[ x1   y1
  x2   y2
  x3   y3]
How do I do that?

Best Answer

Nathan, use the sortrows command.

Related Solutions

MATLAB: How to sort a matrix based on a specific value and bring the row at the beginning of the file

See if you can put a row at the beginning that's column names, like

c1, c2, c3

Is that a possibility? If so, it makes it easier since you can use readtable().

Then try readtable() to read it in

t=readtable(filename);

Then sort the third column. Extract the third column like

column3 = t.c3;

then see if you can use sort(). Take both outputs of sort. Use the sort order to sort the rows of the other columns. Is this homework? If not, attach your data file.

MATLAB: How to make multiple max in elegant way

you could do

max(max([ x1 x2 x3 x4 x5 .... ]))

Since the first max is evaluated along the columns, I think it should be fast enough. Alternatively, you could of course do X = [ x1 x2 x3 ... ] and then max(X(:)). That's shorter, but depending on the length of your vectors, I would go with the first option. A common alternative is to use sort, e.g.

X_sorted = sort([ x1 x2 ... ]);
xmax = max(X_sorted(end,:))

but since for max, you don't need the matrix to be fully sorted, I would guess that max is actually faster.

Best Answer

Related Solutions

MATLAB: How to sort a matrix based on a specific value and bring the row at the beginning of the file

MATLAB: How to make multiple max in elegant way

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