Re: [xsl] sum of the evaluated values

[Jeni Tennison <jeni at jenitennison dot com>]

Hi Al,

> i have xml:
>   <event type="1" time="3:00">
>   <event type="0" time="2:00">
>   <event type="1" time="4:00">
>   <event type="1" time="5:00">
> and i need sum of the minutes: number(substring-before(@time,':'))
> only where @type=1.
>
> How it can  be done?

Several ways. If you're using Saxon, you could use its extension
saxon:sum() function:

  <xsl:value-of
    select="saxon:sum(event[@type = 1],
              saxon:expression('substring-before(@time,
                                                 &quot;:&quot;)')" />

Otherwise, if you're happy using extension functions then you could
build a result tree fragment of elements with the relevant values,
convert it to a node set using the appropriate node-set() extension
function for your processor, and then use the sum() function:

  <xsl:variable name="hours">
    <xsl:for-each select="event[@type = 1]">
      <hour>
        <xsl:value-of select="substring-before(@time, ':')" />
      </hour>
    </xsl:for-each>
  </xsl:variable>
  <xsl:value-of select="sum(exsl:node-set($hours)/hour)" />

If you want a pure XSLT 1.0 method, one way is to create your own
recursive template especially for the events that you're using, as
follows:

<xsl:template name="totalTime">
  <xsl:param name="events" select="event" />
  <xsl:param name="subtotal" select="0" />
  <xsl:choose>
    <xsl:when test="$events">
      <xsl:call-template name="totalTime">
        <xsl:with-param name="events"
                        select="$events[position() > 1]" />
        <xsl:with-param name="subtotal"
          select="$subtotal + substring-before($events[1], ':')" />
      </xsl:call-template>
    </xsl:when>
    <xsl:otherwise>
      <xsl:value-of select="$subtotal" />
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>

You can call the above template simply with:

  <xsl:call-template name="totalTime" />

from the parent of the event elements.

Finally, you could use a more generic template - I'm sure that Dimitre
has one for summing - in which case all you have to do is write the
code for the template that gives the value for the event. I'm sure
Dimitre will tell you more about how to use that if you ask.

I hope that helps,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/


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