Re: [xsl] Calculating cumulative values

["Andrew Welch" <andrew.j.welch@xxxxxxxxx>]

On 2/3/07, Simon Shutter <simon@xxxxxxxxxxx> wrote:
> Hello,
>
> Here is a tricky (to me) problem that requires looping over several sets and
> calculating cumulative values (y2) from x and y1.  That is, for each x, set
> y2 to be equal to the cumulative value of y1 as shown in the example output
> below.
>
> I made my best attempt with the stylesheet below, which I know is quite
> incorrect but wanted to show I did actually try to solve the problem.  I am
> now bogged down with the use of the variable element.
>
> Any assistance would be greatly appreciated,
>
> Simon
>
> ---------------------------------------------
> Input
> ---------------------------------------------
>
> <root id="theroot">
>   <set id="1">
>     <point x="1" y1="2" />
>     <point x="1" y1="3" />
>     <point x="1" y1="0" />
>     <point x="1" y1="2" />
>     <point x="1" y1="2" />
>     <point x="2" y1="3" />
>     <point x="2" y1="0" />
>     <point x="2" y1="2" />
>     <point x="3" y1="2" />
>     <point x="3" y1="3" />
>     <point x="3" y1="1" />
>     <point x="3" y1="2" />
>     <point x="3" y1="2" />
>   </set>
>   <set id="2">
>     <point x="1" y1="2" />
>     <point x="1" y1="3" />
>     <point x="1" y1="0" />
>     <point x="1" y1="2" />
>     <point x="2" y1="2" />
>     <point x="3" y1="2" />
>     <point x="3" y1="2" />
>     <point x="3" y1="2" />
>   </set>
>   <set id="n">
>     <point x="1" y1="2" />
>     <point x="1" y1="3" />
>     <point x="1" y1="2" />
>     <point x="2" y1="3" />
>     <point x="2" y1="0" />
>     <point x="2" y1="2" />
>     <point x="3" y1="3" />
>   </set>
> </root>
>
> ---------------------------------------------
> Desired output
> ---------------------------------------------
> <root id="theroot">
>   <set id="1">
>     <point x="1" y1="2" y2="2"/>
>     <point x="1" y1="3" y2="5"/>
>     <point x="1" y1="0" y2="5"/>
>     <point x="1" y1="2" y2="7"/>
>     <point x="1" y1="2" y2="9"/>
>     <point x="2" y1="3" y2="3"/>
>     <point x="2" y1="0" y2="3"/>
>     <point x="2" y1="2" y2="5"/>
>     <point x="3" y1="2" y2="2"/>
>     <point x="3" y1="3" y2="5"/>
>     <point x="3" y1="1" y2="6"/>
>     <point x="3" y1="2" y2="8"/>
>     <point x="3" y1="2" y2="10"/>
>   </set>
>   <set id="2">
>     <point x="1" y1="2" y2="2"/>
>     <point x="1" y1="3" y2="5"/>
>     <point x="1" y1="0" y2="5"/>
>     <point x="1" y1="2" y2="7"/>
>     <point x="2" y1="2" y2="2"/>
>     <point x="3" y1="2" y2="2"/>
>     <point x="3" y1="2" y2="4"/>
>     <point x="3" y1="2" y2="6"/>
>   </set>
>   <set id="n">
>     <point x="1" y1="2" y2="2"/>
>     <point x="1" y1="3" y2="5"/>
>     <point x="1" y1="2" y2="7"/>
>     <point x="2" y1="3" y2="3"/>
>     <point x="2" y1="0" y2="3"/>
>     <point x="2" y1="2" y2="5"/>
>     <point x="3" y1="3" y2="3"/>
>   </set>
> </root>
>
> ---------------------------------------------
> Prototype stylesheet - just to show I tried
> ---------------------------------------------
> <?xml version="1.0" encoding="utf-8"?>
> <xsl:stylesheet version="1.0"
>     xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
> <xsl:variable name="tempy" select="5"/>
> <!-- Convert root and all elements tags 'as is'  -->
> <xsl:template match="@*|node()">
>   <xsl:copy>
>     <xsl:apply-templates select="@*|node()"/>
>   </xsl:copy>
> </xsl:template>
> <xsl:template match="//point">
>   <xsl:copy>
>     <xsl:copy-of select="@*"/>
>     <xsl:for-each select="@y1">
>       <xsl:attribute name="y2">
>         <xsl:choose>
>           <xsl:when test=". &gt; $tempy">
>             <xsl:value-of select="$tempy * ."/>
>           </xsl:when>
>           <xsl:otherwise>
>             <xsl:value-of select="$tempy + ."/>
>           </xsl:otherwise>
>         </xsl:choose>
>       </xsl:attribute>
>     </xsl:for-each>
>   </xsl:copy>
> </xsl:template>
> </xsl:stylesheet>

You can just use XPath here, no need for recursion:

<xsl:template match="point">
<xsl:copy>
  <xsl:copy-of select="@*"/>
  <xsl:attribute name="y2">
    <xsl:value-of select="sum(./@y1|preceding-sibling::point[@x =
current()/@x]/@y1)"/>
  </xsl:attribute>
</xsl:copy>
</xsl:template>

cheers
andrew