Subject: [xsl] Network diagram - node set intersection From: cknell@xxxxxxxxxx Date: Mon, 23 Feb 2004 12:34:53 -0500 |
==========> Direction of graph ______ | | / |__B__| ______/ \_____ | | | | |__A__| |__D__| \ / \ ______/ | | |__C__| I'm working on producing a network diagram in SVG by processing an XML document with XSLT. Above is a symbolic representation of the output. The relationship between nodes in the graph can't be represented directly in XML because it isn't a tree (Node D has two parents which isn't allowed in XML). Here is a simplified sample of the XML document: <network> <node> <node-id>A</node-id> <predecessor-id></predecessor-id> <successor-id>B</successor-id> </node> <node> <node-id>B</node-id> <predecessor-id>A</predecessor-id> <successor-id>D</successor-id> </node> <node> <node-id>C</node-id> <predecessor-id>A</predecessor-id> <successor-id>D</successor-id> </node> <node> <node-id>D</node-id> <predecessor-id>B</predecessor-id> <predecessor-id>C</predecessor-id> <successor-id></successor-id> </node> </network> In my stylesheet I have a template that matches <node>. For the purpose of positioning the SVG elements I want to determine how many other nodes have a <predecessor-id> that matches one of the <predecessor-id> children of the context <node>. In addition to determining how many "siblings" a <node> has, I also want to know where the context node is in document order relation to these "siblings". The <node> elements with common <predecessor-id> values would be, in the context of the network diagram, "siblings". Of course in the XML document all the <node> elements are siblings in the XPath sense. To determine the number of siblings a <node> element has, I thought I would count the elements in the intersection of the set of <predecessor-id> children of the context node with the set of <predecessor-id> children of all the other <node> elements. I modelled the expression on the example shown on page 425 of the XSLT Programmer's Reference 2nd Edition. Here is a simplfied stylesheet: <?xml version="1.0" encoding="UTF-8" ?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="xml" indent="yes" encoding="UTF-8" /> <xsl:template match="/"> <xsl:apply-templates /> </xsl:template> <xsl:template match="network"> <xsl:apply-templates /> </xsl:template> <xsl:template match="node"> <xsl:variable name="this-node-id" select="node-id" /> <xsl:variable name="this-predecessor-nodes" select="predecessor-id" /> <xsl:variable name="other-predecessor-nodes" select="/network/node[node-id != $this-node-id]" /> <xsl:variable name="sibling-cnt" select="count($this-predecessor-nodes[count(. | $other-predecessor-nodes) != count($other-predecessor-nodes)])" /> This node id = <xsl:value-of select="$this-node-id" /> Sibling count = <xsl:value-of select="$sibling-cnt" /> </xsl:template> </xsl:stylesheet> This yielded the following output: <?xml version="1.0" encoding="UTF-8"?> This node id = A Sibling count = 1 This node id = B Sibling count = 1 This node id = C Sibling count = 1 This node id = D Sibling count = 2 It the intersection operation didn't do what I expected. I expected that nodes A and D would have a Sibling count of 0 and that nodes B and C would each have a sibling count of 1. Could anyone tell me where I'm going wrong and point me in the right direction? Thanks. -- Charles Knell cknell@xxxxxxxxxx - email XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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