fn.subsequence( $sourceSeq as ValueIterator, $startingLoc as Number, [$length as Number] ) as ValueIterator
Returns the contiguous sequence of items in the value of $sourceSeq beginning at the position indicated by the value of $startingLoc and continuing for the number of items indicated by the value of $length.
In the two-argument case, returns:
$sourceSeq[fn:round($startingLoc) le $p]
In the three-argument case, returns:
$sourceSeq[fn:round($startingLoc) le $p and $p lt fn:round($startingLoc) + fn:round($length)]
If $sourceSeq is the empty sequence, the empty sequence is returned.
If $startingLoc is zero or negative, the subsequence includes items from the beginning of the $sourceSeq.
If $length is not specified, the subsequence includes items to the end of $sourceSeq.
If $length is greater than the number of items in the value of $sourceSeq following $startingLoc, the subsequence includes items to the end of $sourceSeq.
The first item of a sequence is located at position 1, not position 0.
For detailed type semantics, see Section 7.2.13 The fn:subsequence functionFS.
The reason the function accepts arguments of type xs:double is that many computations on untyped data return an xs:double result; and the reason for the rounding rules is to compensate for any imprecision in these floating-point computations.
A sequence of items (as a ValueIterator) from which a subsequence will be
selected. If you pass in a single value,
it is treated as a ValueIterator with that single item; therefore, if you
pass in an array, |
|$startingLoc||The starting position of the start of the subsequence.|
|$length||The length of the subsequence.|
var seq = xdmp.arrayValues(["item1", "item", "item3", "item4" , "..."]); fn.subsequence(seq, 4) => (item4, ...) var seq = xdmp.arrayValues(["item1", "item", "item3", "item4" , "..."]); fn.subsequence(seq, 3, 2) => (item3, item4)