UNIQUE Unique

Section: Array Generation and Manipulations

Usage

Returns a vector containing the unique elements of an array. The first form is simply 
   y = unique(x)

where x is either a numerical array or a cell-array of strings. The result is sorted in increasing order. You can also retrieve two sets of index vectors 

   [y, m, n] = unique(x)

such that y = x(m) and x = y(n). If the argument x is a matrix, you can also indicate that FreeMat should look for unique rows in the matrix via 

   y = unique(x,'rows')

and 

   [y, m, n] = unique(x,'rows')

Example

Here is an example in row mode 
--> A = randi(1,3*ones(15,3))

A = 
 1 1 1 
 3 2 2 
 1 3 3 
 2 2 1 
 1 3 1 
 2 3 1 
 2 2 3 
 1 2 2 
 3 3 3 
 2 1 1 
 2 1 1 
 2 3 2 
 1 1 2 
 2 3 1 
 3 3 2 

--> unique(A,'rows')

ans = 
 1 1 1 
 1 1 2 
 1 2 2 
 1 3 1 
 1 3 3 
 2 1 1 
 2 2 1 
 2 2 3 
 2 3 1 
 2 3 2 
 3 2 2 
 3 3 2 
 3 3 3 

--> [b,m,n] = unique(A,'rows');
--> b

ans = 
 1 1 1 
 1 1 2 
 1 2 2 
 1 3 1 
 1 3 3 
 2 1 1 
 2 2 1 
 2 2 3 
 2 3 1 
 2 3 2 
 3 2 2 
 3 3 2 
 3 3 3 

--> A(m,:)

ans = 
 1 1 1 
 1 1 2 
 1 2 2 
 1 3 1 
 1 3 3 
 2 1 1 
 2 2 1 
 2 2 3 
 2 3 1 
 2 3 2 
 3 2 2 
 3 3 2 
 3 3 3 

--> b(n,:)

ans = 
 1 1 1 
 3 2 2 
 1 3 3 
 2 2 1 
 1 3 1 
 2 3 1 
 2 2 3 
 1 2 2 
 3 3 3 
 2 1 1 
 2 1 1 
 2 3 2 
 1 1 2 
 2 3 1 
 3 3 2

Here is an example in vector mode 

--> A = randi(1,5*ones(10,1))

A = 
 3 
 5 
 5 
 1 
 3 
 4 
 1 
 5 
 4 
 1 

--> unique(A)

ans = 
 1 
 3 
 4 
 5 

--> [b,m,n] = unique(A,'rows');
--> b

ans = 
 1 
 3 
 4 
 5 

--> A(m)

ans = 
 1 
 3 
 4 
 5 

--> b(n)

ans = 
 3 
 5 
 5 
 1 
 3 
 4 
 1 
 5 
 4 
 1

For cell arrays of strings. 

--> A = {'hi','bye','good','tell','hi','bye'}

A = 
 [hi] [bye] [good] [tell] [hi] [bye] 

--> unique(A)

ans = 
 [bye] [good] [hi] [tell]