Re: Node Selection

Decarli, Jim 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.
> Here is an example of the xml.
> <Part> 
> 	<PartNumber>978599</PartNumber> 
> 	<Activity> 
> 		<ActivityLocation> 
> 			<DepartmentNumber>07</DepartmentNumber> 
> 			<DepartmentName>Grinding</DepartmentName> 
> 		</ActivityLocation> 
> 		<Status> 
> 			<Code>I</Code> 
> 			<Description>In-Process</Description> 
> 		</Status> 
> 		<Date>20010521</Date> 
> 		<Time>180800</Time> 
> 	</Activity>
> 	<Activity> 
> 		<ActivityLocation> 
> 			<DepartmentNumber>07</DepartmentNumber> 
> 			<DepartmentName>Grinding</DepartmentName> 
> 		</ActivityLocation> 
> 		<Status> 
> 			<Code>R</Code> 
> 			<Description>Received</Description> 
> 		</Status> 
> 		<Date>20010520</Date> 
> 		<Time>081800</Time> 
> 	</Activity>
> 	<Activity> 
> 		<ActivityLocation> 
> 			<DepartmentNumber>05</DepartmentNumber> 
> 			<DepartmentName>Shipping</DepartmentName> 
> 		</ActivityLocation> 
> 		<Status> 
> 			<Code>S</Code> 
> 			<Description>Shipped</Description> 
> 		</Status> 
> 		<Date>20010523</Date> 
> 		<Time>073300</Time> 
> 	</Activity>
> 	<Activity> 
> 		<ActivityLocation> 
> 			<DepartmentNumber>05</DepartmentNumber> 
> 			<DepartmentName>Shipping</DepartmentName> 
> 		</ActivityLocation> 
> 		<Status> 
> 			<Code>R</Code> 
> 			<Description>Received</Description> 
> 		</Status> 
> 		<Date>20010523</Date> 
> 		<Time>060700</Time> 
> 	</Activity>
> </Part>

Hi Jim,

This problem is solved best using a generic max() template. Or you can use my
generic sort() template, which allows only the highest k out of N nodes to be
produced -- in your case k=1.

The other alternatives -- xsl:sort on the full node-set and using only the
first/last node from the nodelist; using a custom-made max() template -- these are
wasting both space and time.

The code of the generic templates for:
 generic max(), 
 generic min(),
 generic binSearch(),
 generic sort()

can be downloaded at 
http://www.vbxml.com/downloads/default.asp?id=v2001611171627

Some more detailed explanation of the concept of generic templates and their
implementation using template references can be found at:

http://lists.fourthought.com/pipermail/exslt/2001-May/000169.html


Cheers,
Dimitre.

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