There are two main approaches to grouping:
(a) the "not(x = preceding::x)" method
(b) the Muenchian method
Method (a) works only where the grouping key is the string-value of a
node; this is because it relies on the special properties of "=" when
comparing two node-sets. Where the grouping key is anything else (e.g.
the first character of the string value), you need to use Muenchian
grouping.
Michael Kay
Software AG
home: Michael(_dot_)H(_dot_)Kay(_at_)ntlworld(_dot_)com
work: Michael(_dot_)Kay(_at_)softwareag(_dot_)com
-----Original Message-----
From: owner-xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
[mailto:owner-xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com] On Behalf Of
Thomas_M
Sent: 27 September 2002 16:27
To: 'xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com'
Subject: [xsl] Sorting Question: Muenchian method? Substring in Key?
Hello. This is my first XSLT project. I'm having trouble with
grouping sorted items (seems to be a common theme). I have a
XML file like this
(simplified):
<topics>
<topic>Anteater</topic>
<topic>Aardvark</topic>
<topic>Beetle, Smaller European Elm Bark</topic>
<topic>Beetle, American Burying</topic>
<topic>Chimpanzee</topic>
</topics>
I would like the output to be sorted and grouped, with each
group getting a
heading:
A
Aardvark
Anteater
B
Beetle, American Burying
Beetle, Smaller European Elm Bark
C
Chimpanzee
The corresponding part of my XSL is below.
<xsl:template match="topics">
<table border="1">
<xsl:for-each select="topic">
<xsl:sort select="."/>
<xsl:variable name="previndex" select="position()-1"/>
<xsl:if test="not(substring(.,1,1)
= substring(/topics/topic[$previndex],1,1))">
<tr><th><xsl:value-of
select="substring(.,1,1)"/></th></tr>
</xsl:if>
<tr>
<td><xsl:value-of select="."/></td>
</tr>
</xsl:for-each>
</table>
</xsl:template>
As you can see, I'm comparing an element in a sorted node-set
with a document-order node-set. This works only if the XML is
pre-sorted. Is there a way to create the sorted node-set
first, so that I can both traverse and use it in my test?
I have seen a few examples of the Muenchian method, and it
would seem this is another (perhaps better) way solve my
problem. However, I've tried several times to implement it
and can't seem to get it right (can you use a substring in a key?)
Thanks for any insight,
- Mark.
--
Mark Thomas |_|
Internet Systems Architect -+-
User Technology Associates, Inc. |
Thomas_M(_at_)bls(_dot_)gov /-\
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