[xsl] Re: Multi-level grouping using variables

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

At 2004-01-09 18:17 -0500, kakridge@xxxxxxxxxxxxx wrote:
> I have been having a problem with grouping.  If I have:
> ...
> How can I group each grade, and within each grade, group all tutors with
> their students?

By using variables and multi-level grouping.  This allows you to easily 
detect groups in a subset scope of the document ... the Muenchian method 
works with document-wide scope.  Note how the principles are similar, but I 
came up with the variable-based approach for a customer who needed three 
levels of grouping and the Muenchian method for that deep a level was 
getting very complex to maintain and understand.

An example is below.

I hope this helps.

...................... Ken

p.s. in our hands-on training we teach all of axis-, variable- and 
key-based grouping methods for XSLT 1.0 (the Muenchian method is the 
key-based method) ... we've just rescheduled our Washington course to March 
15-19 ... announcements will be made soon, details on our home page ... 
other cities are also being planned so check for a location near you.


t:\ftemp>type kakridge.xml
<School>
        <Grade>
                <Students>
                        <Student>
                                <Name>Bob</Name>
                                <Tutor>Mary Smith</Tutor>
                        </Student>
                        <Student>
                                <Name>Joe</Name>
                                <Tutor>Mike Smith</Tutor>
                        </Student>
                        <Student>
                                <Name>Ken</Name>
                                <Tutor>Mary Smith</Tutor>
                        </Student>
                </Students>
                <Name>Kindergarten</Name>
        </Grade>
        <Grade>
                <Students>
                        <Student>
                                <Name>Ted</Name>
                                <Tutor>Mary Smith</Tutor>
                        </Student>
                        <Student>
                                <Name>Sammy</Name>
                                <Tutor>Mike Smith</Tutor>
                        </Student>
                </Students>
                <Name>First</Name>
        </Grade>
</School>

t:\ftemp>type kakridge.xsl
<?xml version="1.0" encoding="iso-8859-1"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
                version="1.0">

<xsl:output method="text"/>

<xsl:template match="/">
  <xsl:for-each select="/School/Grade">
    <xsl:variable name="students" select="Students/Student"/>
    <xsl:for-each select="$students">
      <xsl:if test="generate-id(.)=
                    generate-id($students[Tutor=current()/Tutor])">
Grade: <xsl:value-of select="../../Name"/>
Tutor: <xsl:value-of select="Tutor"/>
Students: <xsl:for-each select="$students[Tutor=current()/Tutor]">
            <xsl:if test="position()>1">,</xsl:if>
            <xsl:value-of select="Name"/>
          </xsl:for-each>
          <xsl:text>
</xsl:text>
      </xsl:if>
    </xsl:for-each>
  </xsl:for-each>
</xsl:template>

</xsl:stylesheet>

t:\ftemp>saxon kakridge.xml kakridge.xsl

Grade: Kindergarten
Tutor: Mary Smith
Students: Bob,Ken

Grade: Kindergarten
Tutor: Mike Smith
Students: Joe

Grade: First
Tutor: Mary Smith
Students: Ted

Grade: First
Tutor: Mike Smith
Students: Sammy

t:\ftemp>rem Done


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G. Ken Holman                 mailto:gkholman@xxxxxxxxxxxxxxxxxxxx
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