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.conj()

A.diff()

A.isect()

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:

A.union()