Re: [xsl] Re: RE: newbie: xsl:key and summation of substrings

["Christopher Giblin" <CGI@xxxxxxxxxxxxxx>]

Thanks,  but your solution seems like home-brew  - I prefer  a portable
100% XLST solution.
Sorry if I misinterpret your recommendation.
Cheers, chris



                                                                                                                                 
                    Dimitre Novatchev                                                                                            
                    <dnovatchev@xxxxxxxxx>             To:     michael.h.kay@xxxxxxxxxxxx                                        
                    Sent by:                           cc:     xsl-list@xxxxxxxxxxxxxxxxxxxxxx                                   
                    owner-xsl-list@xxxxxxxxxxxx        Subject:     [xsl] Re: RE: newbie: xsl:key and summation of substrings    
                    rytech.com                                                                                                   
                                                                                                                                 
                                                                                                                                 
                    12/09/2001 09:34 PM                                                                                          
                    Please respond to xsl-list                                                                                   
                                                                                                                                 
                                                                                                                                 



> Here are three ways to sum over a computed quantity:
>
> * Create a result tree fragment containing nodes whose value is the
computed
> number, and use sum(xx:node-set($rtf//value)) to do the summation, where
> xx:node-set() is your vendor's extension function for converting an RTF
to a
> node-set
>
> * Use a recursive named template [this is the only standard XSLT 1.0
> solution]
>
> * Use the saxon extension function saxon:sum($nodes, saxon:expression
(...))

> > I want to sum the "freespace", but sum(//disk/freespace)
> > won't work because
> > freespace is not a number due to the trailing "MB".

The first of the above solutions requires inappropriate amount of memory
and time.

The third ties us to a proprietary (although one of the best) XSLT
processor.

The second is too-general, as one can achieve almost anything in XSLT with
recursion. It would be almost equivalent to say: "Use arithmetic rules".

Here's another, more practical way, since it uses a "library function" --
transformAndSum:

http://sources.redhat.com/ml/xsl-list/2001-11/msg00831.html

This is ***the*** general solution for all such problems belonging to this
"transform and sum" class of problems...

Having such a general solution available in pure XSLT shows that any
"dynamic
module" effort is very limited and therefore not applicable (== of any use)
in the
general cases.

Re-Using the ready-made "transform and sum" function described in the above
link
gives us the following:

<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
xmlns:func-transform="f:func-transform"
exclude-result-prefixes="xsl func-transform"
>
   <xsl:import href="transform-and-sum.xsl"/>

   <xsl:output method="text"/>

   <func-transform:func-transform/>

    <xsl:template match="/">
      <xsl:call-template name="transform-and-sum">
        <xsl:with-param name="pFuncTransform"
                        select="document('')/*/func-transform:*[1]"/>
        <xsl:with-param name="pList" select="//freespace"/>
      </xsl:call-template>
    </xsl:template>

    <xsl:template match="func-transform:*">
      <xsl:param name="arg" select="0"/>
      <xsl:value-of select="substring-before($arg, ' ')"/>
    </xsl:template>

</xsl:stylesheet>


When this transformation is applied on the following (your) source xml:

<disks>
  <disk>
    <freespace>1235 MB</freespace>
  </disk>
  <disk>
    <freespace>40 MB</freespace>
  </disk>
  <disk>
    <freespace>75 MB</freespace>
  </disk>
</disks>

The result is:

1350


Hope this helped.

Cheers,
Dimitre Novatchev.




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