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Re: Re: Re: Node Selection
- To: Dimitre Novatchev <dnovatchev at yahoo dot com>, Jeni Tennison <mail at jenitennison dot com>, xsl-list at lists dot mulberrytech dot com
- Subject: Re: [xsl] Re: Re: Node Selection
- From: Dimitre Novatchev <dnovatchev at yahoo dot com>
- Date: Fri, 15 Jun 2001 12:18:49 -0700 (PDT)
- Cc: "Decarli, Jim" <Jim dot Decarli at fishersci dot com>
- Reply-To: xsl-list at lists dot mulberrytech dot com
OOppss...
> <xsl:value-of select="concat($n1/Date, $n1/Time)
> >
> concat($n1/Date, $n1/Time) " />
^^^ ^^^
Must be:
<xsl:value-of select="concat($n1/Date, $n1/Time)
>
concat($n2/Date, $n2/Time) " />
Dimitre Novatchev.
--- Dimitre Novatchev <dnovatchev@yahoo.com> wrote:
> Hi Jeni,
> Moving from O(N*Log2(N)) to just O(N)is a great step forward.
>
> Now I understand that you didn't offer this solution, because someone had just
> said
> he "i felt afraid, when i saw jeni's example"...
>
> So, the next step will make your solution also look quite simple -- and you know
> what this step is -- stop writing customised max() templates on every occasion and
> use just one generic max() template. I'm just quoting one of your messages, with
> small adjustments:
>
> <date-timeMax:max />
>
> <xsl:template match="/">
> <xsl:text>Maximum value is: </xsl:text>
> <xsl:apply-templates select="document('')/*/date-timeMax:max)" >
> <xsl:with-param name="nodeset" select="//Activity"/>
> </xsl:apply-templates>
> </xsl:template>
>
> <xsl:template match="date-timeMax:max">
> <xsl:param name="nodes" select="/.."/>
> <xsl:param name="n1" select="/.."/>
> <xsl:param name="n2" select="/.."/>
> <xsl:value-of select="concat($n1/Date, $n1/Time)
> >
> concat($n1/Date, $n1/Time) " />
> </xsl:template>
>
> Cheers,
> Dimitre Novatchev.
>
>
> --- Jeni Tennison <mail@jenitennison.com> wrote:
> > Dimitre Novatchev wrote:
> > >> > I am using Xalan for xsl transformations. I have some xml with
> > >> > multiple <Activity> nodes in it for each part that is processed. The
> > >> > activity nodes are not sorted in any way in the xml. I want to
> > >> > select only the latest activity (by Date, Time) to process in the
> > >> > transform for my output to show the last activity scan on this part
> > >> > and ignore all other activity scans.
> > >>
> > >> The easiest way to do this is to sort the Activity elements by their
> > >> Date and Time (in descending order), and then choose the first one
> > >> only to go on and process:
> > [snip]
> > >
> > > This is one of the most inefficient ways to find a maximum and Jeni
> > > must know it. In case there are thousands of nodes to be sorted, the
> > > unnecessary wait will be due exactly to following such an advice.
> >
> > Well I did say *easiest* rather than *most efficient* ;)
> >
> > Jim, if you have lots of Activity elements and find that your
> > transformation is unacceptably slow, then you could alternatively
> > use a recursive template. This finds the next following Activity that
> > occurs after this one, and if there is one then applies templates to
> > it in 'latest' mode, and so on recursively through the Activity
> > elements. If there isn't one, it applies templates to the Activity so
> > you can go on and process it.
> >
> > <xsl:template match="Activity" mode="latest">
> > <xsl:variable name="date-time" select="concat(Date, Time)" />
> > <xsl:variable name="next"
> > select="following-sibling::Activity
> > [concat(Date, Time) > $date-time][1]" />
> > <xsl:choose>
> > <xsl:when test="$next">
> > <xsl:apply-templates select="$next" mode="latest" />
> > </xsl:when>
> > <xsl:otherwise>
> > <xsl:apply-templates select="." />
> > </xsl:otherwise>
> > </xsl:choose>
> > </xsl:template>
> >
> > To kick this process off, you need to apply templates to the first
> > Activity element in your Part, in 'latest' mode:
> >
> > <xsl:template match="Part">
> > <xsl:apply-templates select="Activity[1]" mode="latest" />
> > </xsl:template>
> >
> > [Caveat: this template will involve very deep recursion, which might
> > still be a problem on some processors (including Xalan, I believe), if
> > you're unlucky with the ordering of your Activity elements. It also
> > assumes that processors are smart enough to optimise XPath expressions
> > that end in a [1] predicate, and to therefore stop when they find the
> > first node in the path, but that shouldn't be a problem in Xalan.]
> >
> > Cheers,
> >
> > Jeni
> >
> > ---
> > Jeni Tennison
> > http://www.jenitennison.com/
> >
> >
>
>
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