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FunctX XQuery Functions


The distinct XML nodes in a sequence (by node identity)



The functx:distinct-nodes function returns the distinct nodes (based on node identity) in a sequence. It does this without resorting them in document order (it takes the first occurrence of each distinct node).It is different from the built-in fn:distinct-values function in that it returns nodes rather than atomic values, and it does not take into account the values (content) of the nodes, just their identity.

Note: if you want them to be resorted in document order, or you don't care, you can simply use the expression "$nodes/." (without the quotes), which works because the slash operator removes duplicates and resorts. The "." in the expression returns the node itself.

Arguments and Return Type

$nodes node()* the node sequence
return value node()*

XQuery Function Declaration

See XSLT definition.
declare namespace functx = "http://www.functx.com";
declare function functx:distinct-nodes
  ( $nodes as node()* )  as node()* {

    for $seq in (1 to count($nodes))
    return $nodes[$seq][not(functx:is-node-in-sequence(
                                .,$nodes[position() < $seq]))]
 } ;


let $in-xml :=
XQuery ExampleResultsExplanation
     ($in-xml/child, $in-xml/*) )
The two child elements that contain 3 have distinct identities, even if they contain the same content.
     ($in-xml/child[3], $in-xml/*) )
The 3 appears first because it is first in the input sequence.

Depends On

functx:is-node-in-sequenceWhether an XML node is in a sequence, based on node identity

See Also

functx:distinct-deepThe XML nodes with distinct values, taking into account attributes and descendants
fn:distinct-valuesThe distinct atomic values in a sequence


Published OnLast UpdatedContributor(s)
2006-06-272007-02-26Priscilla Walmsley, Datypic, pwalmsley@datypic.com, http://www.datypic.com
Datypic XQuery Services

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