Question

I have a small fixed set of nodes: <a>, <b>, <c>, <d>. Each node can have a value of either 1 or 0.
Also, each node has a weight: 1, 2, 3, 4, respectively. Node attributes are not used.
How can I sum the value of each node multiplied by its weight using XSLT 1.0? Example:

<a>0</a>
<b>1</b>
<c>0</c>
<d>1</d>

Sum: 6

<a>1</a>
<b>1</b>
<c>0</c>
<d>0</d>

Sum: 3

<a>0</a>
<b>1</b>
<c>1</c>
<d>1</d>

Sum: 9

Answer 1

This XSLT 1.0 transformation:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>

 <xsl:template match="/*">
  <xsl:call-template name="sumWeighted"/>
 </xsl:template>

 <xsl:template name="sumWeighted">
   <xsl:param name="pList" select="*"/>
   <xsl:param name="pIndex" select="1"/>
   <xsl:param name="pAccum" select="0"/>

   <xsl:choose>
    <xsl:when test="$pIndex > count($pList)">
     <xsl:value-of select="$pAccum"/>
    </xsl:when>
    <xsl:otherwise>
      <xsl:call-template name="sumWeighted">
        <xsl:with-param name="pList" select="$pList"/>
        <xsl:with-param name="pIndex"
             select="$pIndex+1"/>
        <xsl:with-param name="pAccum"
             select="$pAccum+$pList[$pIndex]*$pIndex"/>
      </xsl:call-template>
    </xsl:otherwise>
   </xsl:choose>
 </xsl:template>
</xsl:stylesheet>

when applied to the provided XML documents:

<t>
    <a>0</a>
    <b>1</b>
    <c>0</c>
    <d>1</d>
</t>

,

<t>
    <a>1</a>
    <b>1</b>
    <c>0</c>
    <d>0</d>
</t>

and

<t>
    <a>0</a>
    <b>1</b>
    <c>1</c>
    <d>1</d>
</t>

produces the wanted results, respectively:

6

3

9

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Reference:

If you want to get your hands dirty with really complicated math calculations using XSLT, see this:

http://fxsl.sourceforge.net/articles/xslCalculator/The%20FXSL%20Calculator.html

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XPath 2.0 / XSLT 2.0 Solution:

Use just this XPath 2.0 one-liner:

   sum(/*/*/(number()*position()))