A.pos( x )

Description:

Get positions of members of a sequence in another sequence.

Syntax:

A.pos(x)

Note:

The function gets positions of all members of sequence x in sequence A and returns null if it cannot find positions for all members of x.

Parameter:

A

A sequence.

x

A sequence.

Option:

@i

Get a monotonically increasing integer sequence.

@c

Get position of the continuous sub-sequence x of sequence A when it appears the first time.

@b

A is by default assumed as an ordered sequence and use binary search to get the position increasingly or decreasingly.

Return value:

Integer sequence

Example:

[6,2,1,4,6,3,7,8].pos([1,4, 6])

[3,4,1]; get an integer sequence of positions of members in sequence [1,4,6] in sequence [6,2,1,4,6,3,7,8] when they first appear in the latter.

[6,2,1,4,6,3,7,8].pos([1,4, 9])

null; return null as member 9 of sequence [1,4, 9]; cannot be found in sequence [6,2,1,4,6,3,7,8].

[6,2,1,4,6,3,7,8].pos@i([1,4,6])

[3,4,5]; use @i option to get a monotonically increasing integer sequence of positions of members in sequence [1,4,6] in sequence [6,2,1,4,6,3,7,8].

[6,2,1,4,6,3,7,8].pos([3,6,4])

[6,1,4].

[6,2,1,4,6,3,7,8].pos@i([3,6,4])

null; use @i option but return null because sub-sequence [3,6,4] whose members’ positions in sequence [6,2,1,4,6,3,7,8] isn’t a monotonically increasing integer sequence does not exist.

[2,1,4,6,3,7,8,4,6,1].pos@c([4,6])

3; get position of the continuous sub-sequence [4,6] in sequence [2,1,4,6,3,7,8,4,6,1] when it first appears.

[1,2,3,4,6,7,8].pos@b([3,1,4,6])

[3,1,4,5]; [1,2,3,4,6,7,8] is an ordered sequence and use binary search to get the position.

Related function:

A.pos()

A.psort()