RE: Use for-each-group to eliminate duplicate output

I haven't studied the logic in detail, but:

(a) You need to think of this as a multiphase transformation. Your existing
code is phase 1, the deduplication is phase 2. 

(b) The output of the first phase will need to be structured as XML, at the
moment it's plain text

(c) Deduplication using xsl:for-each-group (or possibly even using the
simpler distinct-values()) should then be unproblematic. 

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

> -----Original Message-----
> From: cknell@xxxxxxxxxx [mailto:cknell@xxxxxxxxxx] 
> Sent: 21 December 2005 18:11
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  Use for-each-group to eliminate duplicate output nodes?
> 
> I have a transformation during which I'd like to eliminate 
> some duplicate nodes which are generated in the 
> transformation. Below is a sample of a portion of the input 
> document the relevant templates from the XSLT document and 
> the output currently generated.
> 
> I need to eliminate duplicate lines from the output file. If 
> I were post-processing with perl, I'd use a hash to do this. 
> Now that I'm moving into XSLT 2.0, I have the feeling that 
> something similar to a perl hash can be got using 
> <xsl:for-each-group>.
> 
> The actual stylesheet and data document are somewhat more 
> complicated. I hope that I have steered correctly between the 
> Scylla and Charybdis of too much and too little information. 
> Can someone tell me whether <xsl:for-each-group> can be used 
> like a perl hash to eliminate duplicate values, and if so how? Thanks.
> 
> -- Data Document (sample portion)--
> <path>
> <node type="process" id="023">
>   <predecessors>
>      <node type="process" id="020">
>         <predecessors>
>            <node type="process" id="001">
>               <predecessors>
>                  <node type="data-store" id="058"/>
>               </predecessors>
>            </node>
>            <node type="process" id="002">
>               <predecessors>
>                  <node type="data-store" id="059"/>
>               </predecessors>
>            </node>
>         </predecessors>
>      </node>
>   </predecessors>
> </node>
> 
> <node type="process" id="024">
>   <predecessors>
>      <node type="process" id="020">
>         <predecessors>
>            <node type="process" id="001">
>               <predecessors>
>                  <node type="data-store" id="058"/>
>               </predecessors>
>            </node>
>            <node type="process" id="002">
>               <predecessors>
>                  <node type="data-store" id="059"/>
>               </predecessors>
>            </node>
>         </predecessors>
>      </node>
>    </predecessors>
> </node>
> </path>
> 
> These are the templates that process the part of the document shown.:
> 
> -- XSLT document --
> <xsl:template match="/">
>   digraph d{
>   <xsl:apply-templates />
> 		}
> </xsl:template>
> 
> <xsl:template match="path">
>   node_<xsl:value-of select="node/@id" /> ;
>   <xsl:apply-templates mode="set-nodes" />
>   <xsl:apply-templates mode="set-connections" />
> </xsl:template>
> 
> <xsl:template match="predecessors" mode="set-nodes">
>   <xsl:apply-templates mode="set-nodes" />
> </xsl:template>
> 
> <xsl:template match="node" mode="set-nodes">
>   <xsl:apply-templates mode="set-nodes" />
> </xsl:template>
> 
> <xsl:template match="predecessors/node" mode="set-nodes">
>   node_<xsl:value-of select="@id" />
>   <xsl:apply-templates mode="set-nodes" />
> </xsl:template>
> 
> <xsl:template match="node" mode="set-connections">
>   <xsl:variable name="target-node" select="." />
>   <xsl:for-each select="predecessors/node">
>     node_<xsl:value-of select="@id" /> -> node_<xsl:value-of 
> select="$target-node/@id" />
>   </xsl:for-each>
>   <xsl:apply-templates mode="set-connections" />
> </xsl:template>
> 
> Output from existing stylesheet (sorted to make 
> identification of duplicates easier):
> 
> digraph d{
> 	node_001
> 	node_001
> 	node_002
> 	node_002
> 	node_003
> 	node_003
> 	node_004
> 	node_005
> 	node_006
> 	node_007
> 	node_008
> 	node_020
> 	node_020
> 	node_023
> 	node_024
> 	node_028
> 	node_038
> 	node_058
> 	node_058
> 	node_059
> 	node_059
> 	node_060
> 	node_061
> 	node_062
> 	node_063
> 	node_064
> 	node_065
> 
> 	node_001 -> node_020
> 	node_001 -> node_020
> 	node_002 -> node_020
> 	node_002 -> node_020
> 	node_004 -> node_038
> 	node_005 -> node_038
> 	node_006 -> node_038
> 	node_007 -> node_038
> 	node_008 -> node_038
> 	node_020 -> node_023
> 	node_020 -> node_024
> 	node_023 -> node_038
> 	node_024 -> node_038
> 	node_038 -> node_028
> 	node_058 -> node_001
> 	node_058 -> node_001
> 	node_059 -> node_002
> 	node_059 -> node_002
> 	node_060 -> node_003
> 	node_061 -> node_004
> 	node_062 -> node_005
> 	node_063 -> node_006
> 	node_064 -> node_007
> 	node_065 -> node_008
> }
> -- 
> Charles Knell
> cknell@xxxxxxxxxx - email