union (MATLAB Function Reference)

Set union of two vectors

c = union(a,b)
c = union(A,B,'rows')
[c,ia,ib] = union(...)

Description

c = union(a,b)

returns the combined values from a and b but with no repetitions. The resulting vector is sorted in ascending order. In set theoretic terms, c = a

b. a and b can be cell arrays of strings.

c = union(A,B,'rows')

when A and B are matrices with the same number of columns returns the combined rows from A and B with no repetitions.

[c,ia,ib] = union(...)

also returns index vectors ia and ib such that
c = a(ia) and c = b(ib) or, for row combinations, c = a(ia,:) and
c = b(ib,:).

Examples

a = [-1 0 2 4 6];     
b = [-1 0 1 3];
[c,ia,ib] = union(a,b);
c =

    -1     0     1     2     3     4     6

ia =

     3     4     5

ib =

     1     2     3     4