Unique function for rows with switched elements

Find unique rows in a 2-element matrix, when rows have switched elements. E.g. when row "1 5" and row "5 1" are both present.

This Matlab function provides a way to find:

1. unique 2-element rows, when rows have switched elements ("u"), i.e., for example, both rows "1 5" and "5 1" are present in the input matrix,
2. rows with switched elements ("s"), and
3. indices of rows with switched elements ("is").

Note: this function is designed ONLY for 2-column matrices as input.

More details here: https://ch.mathworks.com/matlabcentral/answers/1737050-a-compact-way-to-find-1-unique-rows-when-rows-have-switched-elements-2-rows-with-switched-ele

% Example of usage:
clear all
clc

% input (here, the row "1 2" is repeated as row "2 1" and the the row "1 5" is repeated as row "5 1")
a = [1 2
     4 5
     5 1
     2 1
     1 2
     5 2
     5 1
     1 5
     2 9
     5 1]

% output
[u,s,is] = unique_switch(a)


% command window
>> u =

     1     2
     1     5
     2     9
     4     5
     5     2
     
>> s =

     2     1
     5     1

>> is{:}

ans =

     1
     4
     5


ans =

     3
     7
     8
    10