# pos()

Here’s how to use pos() function.

## A .pos()

Description:

Get the position of a member in a sequence.

Syntax:

A.pos(x)

Note:

The function locates member x in sequence A where x may appear repeatedly. Return null if the member cannot be found; return different values according to different options.

Parameters:

 A A sequence object or an expression that returns one. x A member.

Options:

 @b Use the binary search to query the location. In this case A is by default an ordered sequence. Both increasing and decreasing are applicable. @a Return an n-integer sequence consisting of sequence numbers of all the members that fulfill the query condition. @z Perform the search backwards from the last member; by default perform the search from the first member. @s With an ordered A and the binary search, return the position of x if it is a member of A; otherwise, return the opposite number for the sequence number representing the position where x can be inserted sequentially. @p Find position of the sequence x, which needs to be treated as a single value, in A, which, in this case, is a sequence of sub-sequences. @n Return the result of the length of A plus 1 if x cannot be found in A. This option and @a are mutually exclusive.

Return value:

A sequence number or a sequence composed of sequence numbers

Example:

 A 1 =[1,2,8,4,5,6,7,8] 2 =A1.pos(8) 3 3 =A1.pos@a(8) [3,8] 4 =A1.pos@z(8) 8 5 =A1.pos@az(8) [8,3] 6 =A1.pos@z(9) null 7 =[1,2,3,4,5,6,7,8].pos@b(5) 5 8 =[1,2,4,5,6,7,8].pos@s(3) -3 9 =[[6,2,1,4,6,3,7,8],[1,4,6]].pos@p([1,4,6]) 2 10 =[6,2,1,4,6,3,7,8].pos@n(5) 9

Note:

If A is not ordered, then options @b and @s should not be used, or they may bring about the incorrect results. For example:

 [7,6,1,2,3].pos@b(3) Return null

Related functions:

## A .pos( x )

Description:

Get the positions of sequence members in another sequence.

Syntax:

A.pos(x)

Note:

x is a sequence. The function returns integer sequence p which satisfies A(p)==x, and returns null if it cannot find the positions for all members of x.

Parameters:

 A A sequence x A sequence

Options:

 @i Return a monitonically increasing integer sequence p which satisfies A(p)==x @c Return the position in which sequence x first appears in A. By doing so, the position of sub-sequence x in sequence A can be located. If x is not the sub-sequence of A, then return null. @b Use the binary search to query the location. In this case A is by default assumed as an ordered sequence. Both Increasing and decreasing are applicable

Return value:

A monotonically increasing integer sequence or an integer sequence

Example:

 [6,2,1,4,6,3,7,8].pos@i([1,4,6]) [3,4,5], which is a monitonically increasing integer sequence [6,2,1,4,6,3,7,8].posi([1,4,6]) [3,4,1], which is an integer sequence [1,2,3,4,6,7,8].pos@b([3,1,4,6]) [3,1,4,5] [2,1,4,6,3,7,8].pos@i([8,4,6]) null [2,1,4,6,3,7,8,4,6,1].pos@c([4,6]) 

Related functions:

## pos()

Description:

Get the position of a substring in its parent string.

Syntax:

pos(s1, s2{, begin})

Note:

The function finds the position of substring s2 in the parent string s1, which starts from the position begin, and returns null if the substring cannot be found.

Parameters:

 s1 The parent string where you want to search for the substring. s2 Substring of interest. begin The position from which the search starts; the default search is from the beginning.

Options:

 @z Perform the search leftward starting from begin, while the search will be done rightward by default.

Return value:

Integer type

Example:

 pos("abcdef","def") 4 pos("abcdefdef","def",5) 7 pos("abcdef","defa") (null) pos@z("abcdeffdef","def",7) pos("abcdeffdef","def",7) 4 8