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# union()

Here’s how to use union() functions.

## A .union()

Description:

Compute the union of sequence-type members in a sequence.

Synatax:

A.union()

Note:

The function computes the union of sequence-type members in sequence A so as to get a sequence in which identical members won’t appear repeatedly. Duplicate members in the same sub-sequence will be retained.

Parameter:

 A A sequence whose members are sequences

Return value:

A new sequence created through the union of members of sequence A

Example:

 A 1 =[[1,2,3,4,5],[3,7,8]].union() [1,2,3,4,5,7,8] “3” only appears once 2 =[[1,2,2],[3,4,4],[4]].union() [1,2,2,3,4,4] The duplicate “4” is stripped out. Identical members in the same sub-sequence are not regarded as duplicate ones 3 =[[1,2,2],[2,2,2,3],[2]].union() [1,2,2,2,3] There are three “2s” in the second sub-sequence, so the final result also includes three “2s”

Related function:

A.xunion()

## A .union( x )

Description:

Compute x with each member of the sequence whose members are sequences, and then perform union operation on members of the new sequence.

Synatax:

A.union(x)

Note:

The function loops through sequence A, whose members are sequences, to compute expression x and then performs union operation on members of the resulting sequence.

Parameter:

 A A sequence whose members are sequences x An expression that returns a sequence

Return value:

A sequence created through the union of new members of sequence A

Example:

 A 1 =demo.query("select * from EMPLOYEE where GENDER = 'M' order by NAME") 2 =demo.query("select * from EMPLOYEE where GENDER = 'F' order by NAME") 3 =[A1,A2].union(~.(NAME)) [Rebecca,Ashley,…] Common members of A1 and A2 only appear once, and identical members in the same sub-sequence are not regarded as duplicate ones

Related function: