Re: [xsl] Finding distinct nodes using a function in XSLT 2.0

Subject: Re: [xsl] Finding distinct nodes using a function in XSLT 2.0
From: "Dimitre Novatchev" <dnovatchev@xxxxxxxxx>
Date: Tue, 17 Apr 2007 19:17:47 -0700
On 4/17/07, Scott Lynch <slynch@xxxxxxxxxx> wrote:
Dimitre,

That works nicely.

However, is there any difference between
<xsl:sequence select="."/>
(which works) rather than say
<xsl:sequence select="current-group()[1]"/>
which also works, in the overall template logic?

Hi Scott,


No there isn't any difference (in this case), because as the XSLT2.0 spec says:

"The sequence constructor contained in the xsl:for-each-group element
is evaluated once for each of the groups, in processing order. The
sequences that result are concatenated, in processing order, to form
the result of the xsl:for-each-group element. Within the sequence
constructor, the context item is the initial item of the relevant
group..."

Generally, the context item

('.')

is the "initial item" (the item within the group that is first in
population order) of the group and (I think that by definition) it
should be the same as:

current-group()[1]


And, of course, '.' is much more compact towrite and understand than current-group()[1]

--
Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
To invent, you need a good imagination and a pile of junk
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play





thanks, Scott

-----Original Message-----
From: Dimitre Novatchev [mailto:dnovatchev@xxxxxxxxx]
Sent: Tuesday, April 17, 2007 4:51 PM
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: [xsl] Finding distinct nodes using a function in XSLT 2.0

THe following transformaton s a straightforward solutionto this proble:

<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
>

<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:variable name="vDoc1" as="document-node()"
   select="document('file:///C:/XSLT/Tests/docFoo1.xml')"/>

<xsl:variable name="vDoc2" as="document-node()"
   select="document('file:///C:/XSLT/Tests/docFoo2.xml')"/>

<xsl:template match="/">
  <foo>
   <xsl:for-each-group select="($vDoc1 | $vDoc2)/*/bar"
     group-by="@id">
     <xsl:sort select="current-grouping-key()"/>
     <xsl:sequence select="."/>
   </xsl:for-each-group>
  </foo>
</xsl:template>
</xsl:stylesheet>




-- Cheers, Dimitre Novatchev --------------------------------------- Truly great madness cannot be achieved without significant intelligence. --------------------------------------- To invent, you need a good imagination and a pile of junk ------------------------------------- You've achieved success in your field when you don't know whether what you're doing is work or play


On 4/17/07, Scott Lynch <slynch@xxxxxxxxxx> wrote: > This probably isn't the easiest way to this (suggestions welcome), but > I'm collecting data from two similarly structured source documents and > wanting to build a set of distinct nodes based on a certain attribute > value. Example XML: > > doc1.xml > <foo> > <bar id="a" /> > <bar id="b" /> > <bar id="c" /> > <bar id="d" /> > <bar id="g" /> > </foo> > > doc2.xml > <foo> > <bar id="a" /> > <bar id="b" /> > <bar id="c" /> > <bar id="d" /> > <bar id="e" /> > <bar id="f" /> > </foo> > > Desired resulting node set: > > <foo> > <bar id="a" /> > <bar id="b" /> > <bar id="c" /> > <bar id="d" /> > <bar id="e" /> > <bar id="f" /> > <bar id="g" /> > </foo> > > I'm required to provide a template function (or equivalent set of > templates which returns a node set for use by various for-each > constructs in other processors) which accepts the xpath (e.g. /foo/bar) > and an index attribute (e.g. "id") as parameters and returns a node set > as seen above. > > I've managed to write a function which generates a sorted union (I think > I need them sorted to find the distinct values, correct? sorry, newbie > here..), but have yet to find a way to trim the results set so that it > contains only distinct members. Here's what I have so far: > > <xsl:variable name="compare_file" select="document('doc2.xml')"/> > <xsl:variable name="current_file" select="document('doc1.xml')"/> > > <xsl:function name="con:distinct_rows"> > <!-- Selects the distinct rows from the source docs and --> > <!-- comparison doc --> > <xsl:param name="path"/> > <xsl:param name="key"/> > <xsl:variable name="source_rows" > select="$current_file/saxon:evaluate($path)"/> > <xsl:variable name="compare_rows" > select="$compare_file/saxon:evaluate($path)"/> > <xsl:variable name="sorted_union_rows"> > <xsl:for-each select="$source_rows | $compare_rows"> > <xsl:sort data-type="text" select="./saxon:evaluate($key)"/> > <xsl:sequence select="."/> > </xsl:for-each> > </xsl:variable> > <xsl:sequence select="$sorted_union_rows"/> > <!-- ??? distinct node selector instead ??? --> > </xsl:function> > > > Once I have the sorted union, I've tried various following/previous > sibling selectors but have yet to find a command which generates the > distinct node set (I can find the unique nodes based on the "id" but > that's not really helping me). > > Any suggestions? > > thanks a lot! > Scott Lynch

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