How to count entries in XSLT?

Question

I am quite new to XSLT and I would like to generate a count of participants for a list of events. This is my XML:

<events>
    <event name="christmas"/>
    <event name="halloween"/>
    <event name="easter"/>
    <event name="easter"/>
</events>

What I need is something like this:

Christmas: 1 participant
Halloween: 1 participant
Easter: 2 participants

Can this be done with XSLT in any way?

Thanks for any help!

Answer 1

Try this stylesheet, which uses the Muenchian Method to group the event elements by their @name:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:strip-space elements="*"/>
    <!-- based on 
    http://stackoverflow.com/a/16509871/2115381 
    from Dimitre Novatchev
    --> 
    <xsl:key name="kEventVal" match="event" use="@name"/>

<xsl:template match="*">

            <xsl:apply-templates select=
         "event[generate-id() = generate-id(key('kEventVal',@name)[1])]"/>
</xsl:template>

<xsl:template match="event">
    <xsl:value-of select="@name"/>
    <xsl:text>: </xsl:text>
    <xsl:value-of select="count(key('kEventVal',@name))"/>
    <xsl:text> participant</xsl:text>
    <xsl:if test="count(key('kEventVal',@name)) > 1 ">
        <xsl:text>s</xsl:text>
    </xsl:if>
    <xsl:text>&#10;</xsl:text>
</xsl:template>
</xsl:stylesheet>

Which will generate following output:

christmas: 1 participant
halloween: 1 participant
easter: 2 participants