Min / Max followup

danbush · August 30th, 2005, 12:06 PM

I've reviewed a previous thread about determining the minmum and maximum values in a node-set. I have an interesting related question:

How do you retrieve the minimum or maximum values ONLY ONCE assuming that there are multiple equl values?

For instance, in the follwoing xml file, there are several equal date values:

<?xml version="1.0"?>
<?xml-stylesheet href="sortdates.xsl" type="text/xsl"?>
<timesheet>
<user name="employee name" id="001" />
<projects>
<project name="Project 1" number="23" interval="minutes">
<pending>
<entry date="01/01/2005" duration="20000"/>
<entry date="01/01/2005" duration="3000"/>
<entry date="01/02/2005" duration="36"/>
</pending>
</project>
<project name="Project 2" number="36" interval="hours">
<pending>
<entry date="01/01/2005" duration="20000" />
<entry date="01/01/2005" duration="3000"/>
<entry date="01/02/2005" duration="30"/>
</pending>
</project>
<project name="Project 3" number="45" interval="minutes">
<pending>
<entry date="01/02/2005" duration="20000"/>
<entry date="01/01/2005" duration="1000"/>
<entry date="01/03/2005" duration="2"/>
</pending>
</project>
</projects>

</timesheet>

And the stylesheet to go with it:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">

    <xsl:output method="html"/>

    <xsl:variable name="entries" select=".//entry"/>

    <xsl:template match="/">
    <xsl:for-each select="$entries">

        <xsl:if test="not(//entry/@date < ./@date)">
                lowdate = <xsl:value-of select="./@date"/><br/>
        </xsl:if>

        <xsl:if test="not(//entry/@date > ./@date)">
                highdate = <xsl:value-of select="./@date"/><br/>
        </xsl:if>

    </xsl:for-each>

    <html>
            <head>
                <title>Greeting</title>
                <style type="text/css" media="all">@import "timesheet.css";</style>
            </head>
            <body>
                <h1>
                    testing...<br/>

                </h1>
            </body>
        </html>

    </xsl:template>

</xsl:stylesheet>

which basically prints out the low and high dates in the node set, except that the matching equal values are repeated as follows:

lowdate = 01/01/2005
lowdate = 01/01/2005
lowdate = 01/01/2005
lowdate = 01/01/2005
lowdate = 01/01/2005
highdate = 01/03/2005

testing...

Can anyone suggest something? Thanks...

mhkay · August 31st, 2005, 09:11 AM

You could use the standard Munchian methods to remove duplicates. However, this is an inefficient way of getting min and max anyway. A better approach is to do a sort and take the first/last in the sorted sequence - this won't give you any duplicates.

<xsl:for-each select="xxx">
  <xsl:sort .../>
  <xsl:if test="position()=1">
    <first>...</first>

  <xsl:if test="position()=last()">
    <last>...</last>

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

danbush · August 31st, 2005, 12:02 PM

Thanks Michael, it works like a charm...