Hi Tony,
At 10:57 AM 7/13/2004, you wrote:
So I'd replace the:-
<xsl:for-each
select=".//resource[not(@swgcraft_id=preceding::*/@swgcraft_id)]">
with
<xsl:key name="resource-by-id" match="resource" use="@swgcraft_id"/>
<xsl:variable name="resources" select="//resource"/>
<xsl:variable name="unique-resources"
select="$resources[not(count(.|key('resources-by-id',@swgcraft_id)[1])
= 1)]"/>
but I guess I still need some form of for-each statement too?
Yeah, sorry I didn't wrap it up completely -- now you can have
<xsl:for-each select="$unique-resources">...</xsl:for-each>
...but it will be much more efficient, since the set has already been
collected -- the processor doesn't now have to look at every resource in
the document, checking all of their preceding siblings, to establish which
are unique.
This finding-the-unique-one business ("deduplicating") is one of the
relatively few common tasks -- maybe the most important -- for which XPath
1.0 has no direct provision, requiring us XSLT 1.0 hackers to master a
couple of tricky idioms.
Another way to do it you may have just seen in another thread. Instead of
<xsl:variable name="unique-resources"
select="$resources[not(count(.|key('resources-by-id',@swgcraft_id)[1])
= 1)]"/>
(Hey! isn't there a glitch here! isn't that 'not' erroneous? Oops ... I
think I should have offered
$resources[count(.|key('resources-by-id',@swgcraft_id)[1]) = 1]) ...)
you can have
<xsl:variable name="unique-resources"
select="$resources[generate-id() =
generate-id(key('resources-by-id',@swgcraft_id)[1])]"/>
which does the same thing, but in a different way ... and because of the
way a string function is defined to work over a node set, can be obscured
further to simply
$resources[generate-id() = generate-id(key('resources-by-id',@swgcraft_id))]
Cheers,
Wendell
======================================================================
Wendell Piez
mailto:wapiez(_at_)mulberrytech(_dot_)com
Mulberry Technologies, Inc. http://www.mulberrytech.com
17 West Jefferson Street Direct Phone: 301/315-9635
Suite 207 Phone: 301/315-9631
Rockville, MD 20850 Fax: 301/315-8285
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