# union

extract union components of a vector

### Syntax

[v [,ka, kb] ] = union(a,b) [v [,ka, kb] ] = union(a,b,orient)

### Arguments

- a
vector or matrix of numbers or strings

- b
vector of real numbers or strings

- orient
flag with possible values : 1 or "r", 2 or "c".

- v
row vector or matrix of numbers or strings

- ka
row vector of integers

- kb
row vector of integers

### Description

`union(a,b)`

returns a sorted row vector which
retains the unique entries of `[a(:);b(:)]`

.

`union(a,b,"r")`

or
`union(a,b,1)`

returns the matrix formed by the union of
the unique rows of `a`

and `b`

sorted in
lexicographic ascending order. In this case matrices `a`

and `b`

must have the same number of columns.

`union(a,b,"c")`

or
`union(a,b,2)`

returns the matrix formed by the union of
the unique columns of `a`

and `b`

sorted
in lexicographic ascending order. In this case matrices
`a`

and `b`

must have the same number of
rows.

`[v,ka,kb]=union(a,b)`

also returns index vectors
`ka`

and `kb`

such that
`v`

is a sorted combination of the entries
`a(ka)`

and `b(kb)`

.

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