RE: Standard XPath expression for the intersection of two node se ts (Was: RE: How can I test if an node included in a nodeset)

["G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>]

At 00/08/04 10:59 +0200, Oliver Becker wrote:
> I don't know if anybody has mentioned this before:
>
> We had already
>    $nodes1[count(.|$nodes2)=count($nodes2)]
> as intersection expression.
>
> If we add a single exclamation mark
>    $nodes1[count(.|$nodes2)!=count($nodes2)]
> it will become the difference of the two node-sets $nodes1 and $nodes2.

I disagree, though I thought the same at first when saw Mike's great post 
... what you have will be those in $nodes1 not in $nodes2, but not those in 
$nodes2 not in $nodes1.

I figured you would need:

   (   $ns1[count(.|$ns2)!=count($ns2)]
     | $ns2[count(.|$ns1)!=count($ns1)] )

to get the true difference as I understand it, that being all nodes in both 
sets not in the other set.  I have an example below.

I hope this helps.

.......... Ken

T:\ftemp>type diff.xsl
<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
                xmlns:data="ken"
                version="1.0">

<xsl:output method="text"/>

<data:data>
  <item>1</item>
  <item>2</item>
  <item>3</item>
  <item>4</item>
  <item>5</item>
</data:data>

<xsl:template match="/">                         <!--root rule-->
  <xsl:variable name="ns1"
                select="document('')//data:data/item[position()>1]"/>
  <xsl:variable name="ns2"
                select="document('')//data:data/item[position()&lt;5]"/>
  <xsl:for-each select="$ns1[count(.|$ns2)=count($ns2)]">
    Intersection: <xsl:value-of select="."/>
  </xsl:for-each>
  <xsl:for-each select="(   $ns1[count(.|$ns2)!=count($ns2)]
                          | $ns2[count(.|$ns1)!=count($ns1)] )">
    Difference: <xsl:value-of select="."/>
  </xsl:for-each>
</xsl:template>

</xsl:stylesheet>


T:\ftemp>xt diff.xsl diff.xsl

    Intersection: 2
    Intersection: 3
    Intersection: 4
    Difference: 1
    Difference: 5
T:\ftemp>

--
G. Ken Holman                    mailto:gkholman@xxxxxxxxxxxxxxxxxxxx
Crane Softwrights Ltd.             http://www.CraneSoftwrights.com/s/
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