Re: How to specify document order location path for id

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Subject: Re: How to specify document order location path for identical elements with different parents?
From: Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>
Date: Fri, 02 Apr 2004 14:53:34 -0500

At 02:37 PM 4/2/2004, you wrote:

1) What is the number of reports which are coded with either an "a" or "b" where the last "a" or "b" code of the report (in document order) is an "a"?

(correct number is 3. Yes, this has been double checked.)

XPath typically provides several ways to skin any particular cat. But

count(/reportlist/report
  [codelist/code/@type='a' or codelist/code/@type='b']
  [descendant::code[@type='a' or @type='b'][last()]/@type='a'])

will do this.

2) What is the number of reports which are coded with either an "a" or "b" where the last "a" or "b" code of the report (in document order) is a "b".

This looks the same as above, except that final equality test is @type='b' not @type='a'.

In my previous posting I recevied several helpful responses. Unfortunate that I couldn't apply them to my application because my example was too simplified. Specifically, codes in the same report may have different codelist parents, and this seems to be what's at the root of my problem formulating an xpath statement.

It is also possible to write expressions for cases even more general. As always, the trick is in getting the spec right.

Once you do that, if you know XPath, it isn't hard. Experience teaching XSLT suggests that a thorough and more-or-less formal introduction to XPath goes a very long way. "Faking it" proves to be false economy, as the time you saved learning it is more than overtaken by time spend guessing and pulling hair. So take a course that gives due attention to mastering XPath (my company offers one :-), or take the time to work through a decent introduction to the subject.

For completeness, I can also offer you the long version of the first of these:

count(/child::reportlist/child::report
  [child::codelist/child::code/attribute::type='a' or
   child::codelist/child::code/attribute::type='b']
  [descendant::code[attribute::type='a' or attribute::type='b']
    [position() = last()]/attribute::type='a'])

Cheers,
Wendell


======================================================================
Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
Mulberry Technologies, Inc.                http://www.mulberrytech.com
17 West Jefferson Street                    Direct Phone: 301/315-9635
Suite 207                                          Phone: 301/315-9631
Rockville, MD  20850                                 Fax: 301/315-8285
----------------------------------------------------------------------
  Mulberry Technologies: A Consultancy Specializing in SGML and XML
======================================================================

Current Thread
How to specify document order location path for identical elements with different parents? Alan Stein - Fri, 2 Apr 2004 14:38:34 -0500 (EST) Wendell Piez - Fri, 2 Apr 2004 15:03:33 -0500 (EST) <= Andreas L. Delmelle - Fri, 2 Apr 2004 15:06:18 -0500 (EST) G. Ken Holman - Fri, 2 Apr 2004 15:16:32 -0500 (EST) Michael Kay - Fri, 2 Apr 2004 15:30:15 -0500 (EST)

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