# union

Set union of two arrays

## Syntax

## Description

returns the combined data from `C`

= union(`A,B`

)`A`

and `B`

with no repetitions. `C`

is in sorted order.

If

`A`

and`B`

are tables or timetables, then`union`

returns the combined set of rows from both tables. For timetables,`union`

takes row times into account to determine equality, and sorts the output timetable`C`

by row times.

and
`C`

= union(`A,B`

,___,'rows')

treat each row of `C`

= union(`A,B`

,'rows',___)`A`

and each row of `B`

as
single entities and return the combined rows from `A`

and
`B`

, with no repetitions. You must specify
`A`

and `B`

and optionally can specify
`setOrder`

.

The `'rows'`

option does not support cell arrays, unless one
of the inputs is either a categorical array or a datetime array.

`[`

also returns index vectors `C`

,`ia`

,`ib`

]
= union(___)`ia`

and `ib`

using
any of the previous syntaxes.

Generally, the values in

`C`

are a sorted combination of the elements of`A(ia)`

and`B(ib)`

.If the

`'rows'`

option is specified, then the rows of`C`

are a sorted combination of the rows of`A(ia,:)`

and`B(ib,:)`

.If

`A`

and`B`

are tables or timetables, then`C`

is a sorted combination of the rows of`A(ia,:)`

and`B(ib,:)`

.

## Examples

## Input Arguments

## Output Arguments

## Tips

To find the union with respect to a subset of variables from a table or timetable, you can use column subscripting. For example, you can use

`union(A(:,`

, where),B(:,`vars`

))`vars`

is a positive integer, a vector of positive integers, a variable name, a cell array of variable names, or a logical vector. Alternatively, you can use`vars`

`vartype`

to create a subscript that selects variables of a specified type.

## Extended Capabilities

**Introduced before R2006a**