saxon:slice

Selects items from a sequence based on their position.

slice($seq as item()*, $positions as xs:integer*) ➔ item()*

Arguments
	$seq	item()*	The sequence to be filtered
	$positions	xs:integer*	The positions of the items to be selected
Result		item()*

Namespace

http://saxon.sf.net/

Saxon availability

Requires Saxon-PE or Saxon-EE. Implemented since Saxon 11.

Notes on the Saxon implementation

Available since Saxon 11. The function is likely to become superseded by the proposed XPath 4.0 function fn:slice(), which has a slightly different specification. All the functionality except for the use of negative positions (to count from the end) is already available using the XPath 4.0 function fn:items-at(), and other common use cases can be achieved using, for example, fn:foot() and fn:trunk().

Details

For each integer $i in the value of $positions, in order, the function returns:

$seq[$i] if the integer is between 1 and the length of $seq (inclusive)
$seq[count($seq)-$i+1] if the integer is negative and its absolute value is between 1 and the length of $seq (inclusive)
an empty sequence if the integer is zero, or if its absolute value exceeds the length of $seq

For example:

saxon:slice(10 to 20, 5) returns 14
saxon:slice(10 to 20, 5 to 6) returns (14, 15)
saxon:slice(10 to 20, (5, 3, 1)) returns (14, 12, 10)
saxon:slice(10 to 20, -1) returns 20
saxon:slice(10 to 20, -3 to -1) returns (18, 19, 20)
saxon:slice(10 to 20, 0) returns ()
saxon:slice(10 to 20, -2 to +2) returns (19, 20, 10, 11)