MATLAB Function Reference |

**Syntax**

**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)`

`b(ib)`

, or for row combinations, `c = a(ia,:)`

`b(ib,:)`

. If a value appears in both `a`

and `b`

, `union`

indexes its occurrence in `b`

. If a value appears more than once in `b`

or in `a`

(but not in `b`

), `union`

indexes the last occurrence of the value.

**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

**See Also**

`intersect`

, `setdiff`

, `setxor`

, `unique`

, `ismember`

, `issorted`

undocheckout | unique |