Rather than using for-each-group, I would use recursion: tail recursion over
the sequence of columns, testing each one to see if it has the same content
as the next column. You can do this test using deep-equals(): given $i as
the column number

deep-equal(tbody/tr/td[$i], tbody/tr/td[$i+1)

The output of this recursion can be a list of the columns to be included in
the result (in your example (1,2,3,5)) and then you can use this list to
drive the process that builds the output.

[The reason for avoiding for-each-group is that it's not easy in this
situation to compute a grouping key. But it's not impossible, and if
recursion fills you with horrors, it might be easier.)

Regards,

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

> -----Original Message-----
> From: Kevin Bird [mailto:kevin.bird@xxxxxxxxxxxxxxxxxxxxxxx] 
> Sent: 15 January 2010 15:05
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  Grouping adjacent columns in a table
> 
> Hello
> 
> I have an XHTML table which can have an arbitrary number of 
> columns and rows.
> 
> For display purposes, I need to reduce the number of columns 
> by grouping adjacent duplicate columns.
> 
> Therefore.
> 
> <table border="1" rules="all">
> 	<thead>
> <tr>
> 	<th>A</th>
> 	<th>B</th>
> 	<th>C</th>
> 	<th>D</th>
> 	<th>E</th>
> </tr>
> 	</thead>
> 	<tbody>
> <tr>
> 	<td>100</td>
> 	<td>100</td>
> 	<td>200</td>
> 	<td>200</td>
> 	<td>300</td>
> </tr>
> <tr>
> 	<td>400</td>
> 	<td>500</td>
> 	<td>500</td>
> 	<td>500</td>
> 	<td>500</td>
> </tr>
> <tr>
> 	<td>600</td>
> 	<td>600</td>
> 	<td>700</td>
> 	<td>700</td>
> 	<td>800</td>
> </tr>
> <tr>
> 	<td>900</td>
> 	<td>900</td>
> 	<td>900</td>
> 	<td>900</td>
> 	<td>900</td>
> </tr>
> 	</tbody>
> </table>
> 
> becomes
> 
> <table border="1" rules="all">
> 	<thead>
> <tr>
> 	<th>A</th>
> 	<th>B</th>
> 	<th>C,D</th>
> 	<th>E</th>
> </tr>
> 	</thead>
> 	<tbody>
> <tr>
> 	<td>100</td>
> 	<td>100</td>
> 	<td>200</td>
> 	<td>300</td>
> </tr>
> <tr>
> 	<td>400</td>
> 	<td>500</td>
> 	<td>500</td>
> 	<td>500</td>
> </tr>
> <tr>
> 	<td>600</td>
> 	<td>600</td>
> 	<td>700</td>
> 	<td>800</td>
> </tr>
> <tr>
> 	<td>900</td>
> 	<td>900</td>
> 	<td>900</td>
> 	<td>900</td>
> </tr>
> 	</tbody>
> </table>
> 
> as columns 'C' and 'D' contain duplicate values. The real 
> data could contain up to 50 columns and grouping could span 
> several columns.
> 
> I can utilise a XSLT 2.0 solution.
> 
> Any help you be appreciated.
> 
> --
> Kevin