As long as we are offering alternatives, how about XSLT?
<xsl:key name="bound-books" match="Book"
use="l:signature(.)"/>
<xsl:template match="/">
<BookList>
<xsl:apply-templates select=".//Book"/>
</BookList>
</xsl:template>
<xsl:template match="Book"/>
<xsl:template match="Book[. is key('bound-books',l:signature(.))[1]
and exists(key('bound-books',l:signature(.))[2])]">
<xsl:copy-of select="."/>
</xsl:template>
<xsl:function name="l:signature" as="xs:string">
<xsl:param name="book" as="element(Book)"/>
<xsl:value-of select="string-join($book/(Author,Title,Binding),'_')"/>
</xsl:function>
This might translate the requirements even more directly -- drop a
book unless it is the first with its title, author and binding and if
a second of the same title, author and binding can be found.
I *think* that is what was asked for, or the practical equivalent?
Cheers, Wendell
On Thu, May 2, 2019 at 12:21 PM Dimitre Novatchev
dnovatchev(_at_)gmail(_dot_)com
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:
Assuming that there is just one BookBinding for all books with the same title
by the same author and with the same binding, and also assuming that all
books with the same title by the same author are in ** contiguous** bindings
(which is the case with the provided document), then this XPath 2.0
expression selects the wanted Book elements. At least for me it seems less
complex and more understandable than the originally provided expression
"for $b in
/*/*/Book[Author = ../following-sibling::*[1]/Book/Author
and Title = ../following-sibling::*[1]/Book/Title
and not(Binding = ../following-sibling::*[1]/Book/Binding)
][1],
$binding in distinct-values(/*/*/Book[Author = $b/Author and Title =
$b/Title]/Binding)
return
/*/*/Book[Author = $b/Author and Title = $b/Title and Binding =
$binding][1]
On Thu, May 2, 2019 at 5:55 AM Costello, Roger L.
costello(_at_)mitre(_dot_)org
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:
Hello XPath experts!
At the bottom of this message is my XML document. I need an XPath 2.0
expression that returns the result of this query:
Are there any book titles with more than
one binding? If yes, then show the first book
for each binding.
For the below XML document, the query should return these two books:
<Book>
<Author>Sally Smith</Author>
<Title>XYZ</Title>
<Binding>hardcover</Binding>
<Count>1</Count>
<Description>lo lo lo ..</Description>
</Book>
<Book>
<Author>Sally Smith</Author>
<Title>XYZ</Title>
<Binding>softcover</Binding>
<Count>1</Count>
<Description>do do do ..</Description>
</Book>
Notice that the two books have the same author and title but different
binding (hardcover versus softcover).
This XPath 2.0 expression seems to work:
for $i in /Bookstore/BookTitle/Book[1],
$j in /Bookstore/BookTitle/Book[1] return
if (($i ne $j)
and ($i/Author eq $j/Author)
and ($i/Title eq $j/Title)
and ($i/Binding ne $j/Binding)
and ($i = $j/preceding::Book))
then ($i, $j)
else ()
That expression seems awfully complicated. Is there a simpler expression? If
there isn't a simpler expression, then do you see anything missing in the
expression (i.e., something that the expression doesn't take into
consideration)? /Roger
<Bookstore>
<BookTitle>
<Book>
<Author>John Doe</Author>
<Title>ABC</Title>
<Binding>hardcover</Binding>
<Count>1</Count>
<Description>da da da ..</Description>
</Book>
<Book>
<Author>John Doe</Author>
<Title>ABC</Title>
<Binding>hardcover</Binding>
<Count>2</Count>
<Description>za za za ..</Description>
</Book>
</BookTitle>
<BookTitle>
<Book>
<Author>John Doe</Author>
<Title>Foo</Title>
<Binding>softcover</Binding>
<Count>1</Count>
<Description>na na na ..</Description>
</Book>
</BookTitle>
<BookTitle>
<Book>
<Author>Sally Smith</Author>
<Title>XYZ</Title>
<Binding>hardcover</Binding>
<Count>1</Count>
<Description>lo lo lo ..</Description>
</Book>
<Book>
<Author>Sally Smith</Author>
<Title>XYZ</Title>
<Binding>hardcover</Binding>
<Count>2</Count>
<Description>ho ho ho ..</Description>
</Book>
</BookTitle>
<BookTitle>
<Book>
<Author>Sally Smith</Author>
<Title>XYZ</Title>
<Binding>softcover</Binding>
<Count>1</Count>
<Description>do do do ..</Description>
</Book>
</BookTitle>
</Bookstore>
--
Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
To invent, you need a good imagination and a pile of junk
-------------------------------------
Never fight an inanimate object
-------------------------------------
To avoid situations in which you might make mistakes may be the
biggest mistake of all
------------------------------------
Quality means doing it right when no one is looking.
-------------------------------------
You've achieved success in your field when you don't know whether what you're
doing is work or play
-------------------------------------
To achieve the impossible dream, try going to sleep.
-------------------------------------
Facts do not cease to exist because they are ignored.
-------------------------------------
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Sanity is madness put to good use.
-------------------------------------
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