MATLAB Function Reference

unique

Unique elements of a vector

Syntax

• b = unique(A)
  b = unique(A,'rows')
  [b,m,n] = unique(...)
  

Description

b = unique(A) returns the same values as in A but with no repetitions. The resulting vector is sorted in ascending order. A can be a cell array of strings.

b = unique(A,'rows') returns the unique rows of A.

[b,m,n] = unique(...) also returns index vectors m and n such that b = A(m) and A = b(n). Each element of m is the greatest subscript such that b = A(m). For row combinations, b = A(m,:) and A = b(n,:).

Examples

• A = [1 1 5 6 2 3 3 9 8 6 2 4]
  A =
  1     1     5     6     2     3     3     9     8     6     2     4
  
  [b,m,n] = unique(A)
  b =
        1     2     3     4     5     6     8     9
  m =
        2    11     7    12     3    10     9     8
  n =
  1     1     5     6     2     3     3     8     7     6     2     4
  
  A(m)
  ans =
        1     2     3     4     5     6     8     9
  
  b(n)
  ans =
  1     1     5     6     2     3     3     9     8     6     2     4
  

Because NaNs are not equal to each other, unique treats them as unique elements.

• unique([1 1 NaN NaN])
  ans = 
       1 NaN NaN
  

See Also

intersect, ismember, issorted, setdiff, setxor, union

union

unix