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Re: Efficently transposing tokenized data

Subject: Re: Efficently transposing tokenized data
From: "Dimitre Novatchev" <dnovatchev@xxxxxxxxx>
Date: Tue, 4 Nov 2008 17:20:32 -0700
Re:  Efficently transposing tokenized data
THe following solution transforms the initial xml document into a
well-structured matrix (sequence of structured rows), then the
transposition is trivial:



<xsl:stylesheet version="2.0"
	xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
	xmlns:xs="http://www.w3.org/2001/XMLSchema"
	xmlns:my ="my:my"
	exclude-result-prefixes="my xs"
 >
	
	<xsl:output omit-xml-declaration="yes" method="html"/>
	
	<xsl:template match="/">
	  <table>
	    <xsl:apply-templates/>
	  </table>
	</xsl:template>
	
	<xsl:template match="MultiLine">
	  <tr>
	    <xsl:apply-templates select="*/@title"/>
	  </tr>
	
	  <xsl:variable name="vMatrix" as="element()*"
	   select="my:makeMatrix(Line)"/>
	
	  <xsl:for-each select="1 to @samples">
	    <xsl:variable name="vRow" as="xs:integer" select="."/>
	    <tr>
	     <xsl:for-each select="$vMatrix">
				 <td>
				  <xsl:value-of select="mdata[$vRow]"/>
				 </td>
	     </xsl:for-each>
	    </tr>
	  </xsl:for-each>
	</xsl:template>
	
	<xsl:template match="Line/@title">
	  <th>
	    <xsl:value-of select="."/>
	  </th>
	</xsl:template>
	
	<xsl:function name="my:makeMatrix" as="element()*">
	  <xsl:param name="pLines" as="element()*"/>
	
	  <xsl:for-each select="$pLines">
	    <mrow>
	      <xsl:for-each select="tokenize(@data, ' ')">
	        <mdata>
					  <xsl:value-of select="."/>
	        </mdata>
	      </xsl:for-each>
	    </mrow>
	  </xsl:for-each>
	</xsl:function>
</xsl:stylesheet>

when the above transformation is applied against the original input
(".." replaced with "."):

<MultiLine samples="5">
	<Line title="Line 1" data="0.1 0.4 0.6 0.4 0.8" />
	<Line title="Line 2" data="0.4 0.2 0.5 1.4 3.8" />
</MultiLine>

the wanted result is produced:

<table>
   <tr>
      <th>Line 1</th>
      <th>Line 2</th>
   </tr>
   <tr>
      <td>0.1</td>
      <td>0.4</td>
   </tr>
   <tr>
      <td>0.4</td>
      <td>0.2</td>
   </tr>
   <tr>
      <td>0.6</td>
      <td>0.5</td>
   </tr>
   <tr>
      <td>0.4</td>
      <td>1.4</td>
   </tr>
   <tr>
      <td>0.8</td>
      <td>3.8</td>
   </tr>
</table>

-- 
Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
To invent, you need a good imagination and a pile of junk
-------------------------------------
Never fight an inanimate object
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play



On Tue, Nov 4, 2008 at 4:13 PM, Beldaz Jalfrezi <beldazj@xxxxxxxxxxxx> wrote:
> Hi XSL-List members,
>
> I have been learning my way around XSLT (2.0) over the past couple of weeks, principally using Saxon-B 9.1. I have an immediate need to transform existing XML data, initially to HTML. The XML contains, similar to SVG, space-tokenized numerical data held within attributes. What I am having trouble understanding is how to transform several nodes with such data into individual columns of data.
>
> The XML is like this:
> <MultiLine samples="5">
> <Line title="Line 1" data="0.1 0.4 0.6 0.4 0..8" />
> <Line title="Line 2" data="0.4 0.2 0.5 1.4 3.8" />
> </MultiLine>
>
> There can be any number of <Line> nodes (typically 3 or 4) and the number of values (samples) in each data attribute for each <Line> must match the samples attribute of the parent <MultiLine> node. The number of samples can be very long, typically several thousand. At present this is the data that I am being supplied, so regardless of any shortcomings of the structure (although suggestions for improvement are welcome) I am stuck with it.
>
> I want to transform such data into, e.g., HTML columns, like:
> <TABLE>
> <TR>
> <TH>Line 1</TH><TH>Line 2</TH>
> </TR>
> <TR>
> <TD>0.1</TD><TD>0.4</TD>
> </TR>
> <TR>
> <TD>0.4</TD><TD>0.2</TD>
> </TR>
> <TR>
> <TD>0.6</TD><TD>0.5</TD>
> </TR>
> ...
> </TABLE>
>
> I have seen similar questions where people have wanted to transpose HTML table data, but the problem here is that the input data has to be tokenized. I can output the data sequentially for each Line with a template such as:
>  <xsl:template match="Line">
> <TR><TH><xsl:value-of select="@title" /></TH><TR>
>      <xsl:for-each select="tokenize(@data,' ')">
>        <TR><TD>
>            <xsl:value-of select="position()" />
>          </TD></TR>
>            <xsl:value-of select="." />
>      </xsl:for-each>
>  </xsl:template>
>
> To format the data as adjacent columns the only approach I can think of is a for-each loop over the number of samples, and in each case call index-at(tokenize(../Line[n]/@data, ' '), position()) for each Line. But this looks horribly inefficient, since I appear to be tokenizing every @data attribute repeatedly, presumably giving complexity O(count(Line)*samples^2). What would be far more preferable is to tokenize all the lines, and then at each index obtain the appropriate value from each sequence. But I have no idea how to do that in XSLT.
>
> I have spent at least a day trying to solve this conumdrum, so if anyone has any suggestions I would be very grateful.
>
> Kind regards,
>
> Beldaz
>
>
>
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