RE: [xsl] Temporary tree elements and namespaces

Subject: RE: [xsl] Temporary tree elements and namespaces
From: "Michael Kay" <mike@xxxxxxxxxxxx>
Date: Wed, 13 Feb 2008 21:48:15 -0000
I'm having trouble understanding this problem because it says "namespaces"
in the title (and in the prose) but there are no namespaces in the source
document or stylesheet.

The temporary tree seems a bit heavy to me. Why not just have a temporary
sequence of numbers?

>   <xsl:template match="/values">
      <xsl:variable name="taxes" as="xs:decimal*">
        <xsl:for-each select="value">
          <xsl:sequence select="xs:decimal(format-number(., '#.00'))"/>
        </xsl:for-each>
>     </xsl:variable>
>     <xsl:for-each select="$taxes">
>       <xsl:value-of select="."/>
>       <xsl:text> || </xsl:text>
>     </xsl:for-each>
>     <xsl:value-of select="format-number(sum($taxes), '#.00')"/>
>   </xsl:template>

which reduces further to

<xsl:template match="/values">
  <xsl:variable name="taxes" select="value/xs:decimal(format-number(.,
'#.00'))"/>
  <xsl:value-of select="$taxes, format-number(sum($taxes), '#.00')"
separator=" || "/>
</xsl:template>

You could also do the rounding using round-half-to-even(), which would avoid
formatting the number as a string only to convert it back to a number.

Note the general programming style here: as with SQL, it's useful to learn
to think in terms of processing sets of things in bulk without having to
iterate over them.

Michael Kay
http://www.saxonica.com/




> -----Original Message-----
> From: Joco Cruz Morais [mailto:spiderfish@xxxxxxxxx]
> Sent: 13 February 2008 19:47
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: [xsl] Temporary tree elements and namespaces
>
> Hello everyone,
>
> I was about to finish converting a xml document to an excel
> xml file when I noticed that some tax values on the input
> file can have up to 4 decimal places while in the final
> document they are all being rounded to 2 decimal places which
> raises problems when you sum all of them, since the sum of
> the rounding might be different from the rounding of the sum.
> Try 0.123 + 0.234 for example:
> 1: 0.123 => 0.12
> 2: 0.234 => 0.23
> sum: 0.123 + 0.234 = 0.357 => 0.36 (not correct given the
> previous values)
>
> To get rid of this problem I've decided it was a good idea to
> use a temporary tree that saves all the rounded values in
> advance, so I can show them individually and also present a
> correct sum in the end.
> Everything went well with my sample tests but it didn't work
> in the final version. After some wasted hours I've figured
> out that the problem is the default namespace that Excel
> *requires* to be present.
> As soon as I added a default namespace (xmlns="something") to
> my test stylesheet it stopped working too. When I thought
> about it, I realized that maybe the elements in the temporary
> tree weren't binded to the source default namespace and so
> I've added a namespace attribute to the xsl:element which
> unfortunately didn't do anything. What am I doing wrong?
> Below goes both the xml and the xsl files. For the sake of
> simplicity I've cut down a lot of the content and a bit of
> the temp tree to only keep what matters. Also this version is
> working but if you had a default namespace to the stylesheet
> definition the select stops returning any nodes.
> Finally I'm using Saxon 9 (great piece of software btw).
>
> Thanks in advance,
> Joco C. Morais
>
> === XML FILE ===
>
> <?xml version="1.0" encoding="ISO-8859-1"?> <values>
>   <value>0.123</value>
>   <value>0.234</value>
> </values>
>
> === XSL FILE ===
>
> <?xml version="1.0" encoding="ISO-8859-1"?> <xsl:stylesheet
> version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
>   <xsl:output method="text"/>
>   <xsl:template match="/values">
>     <xsl:variable name="taxes" as="item()*">
>       <xsl:for-each select="value">
>         <xsl:element name="tax">
>           <xsl:element name="value">
>             <xsl:value-of select="number(format-number(., '#.00'))"/>
>           </xsl:element>
>         </xsl:element>
>       </xsl:for-each>
>     </xsl:variable>
>     <xsl:for-each select="$taxes">
>       <xsl:value-of select="value"/>
>       <xsl:text> || </xsl:text>
>     </xsl:for-each>
>     <xsl:value-of select="format-number(sum($taxes/value), '#.00')"/>
>   </xsl:template>
> </xsl:stylesheet>

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