MATLAB: Vector Comparison According to Entities

Question

I have the following vector A.

A = [21, 20,2,19, 3, 18, 4,17, 5,16, 6,15, 7,14, 8, 13, 9, 10;…

2, 3 ,21, 4, 20, 5,19, 6,18, 7,17, 8,16, 9,15,10,14,13]

I would like to obtain a 1xN numbering vector where N is the number of columns of A which assigns the same number to columns that are flipped version of each other. (i.e column1 and column3. column1 = [21;2] column3 = [2,21] column1 = flip(column2)). Thus the numbering must be like this

n = [ 1 2 1 3 2 4 3 5 6 7 5 6 7 8 6 9 8 9];

Answer 1

[~,~,n]=unique(sort(A,1).','rows');
n=n(:).';