Re: [xsl] Using XSLT to build an index

["G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>]

At 2011-10-30 14:47 -0700, Mark wrote:
> The list archives did not seem to contain an
> XSLT stylesheet that could index an XML file,
> but I may have missed it. Is it practical to
> write my own XSLT 2 indexing stylesheet? If so,
> I have a bilingual XML file that I want to index.

Where you simply want all words, except your stop
words, collected to automate the index
generation, I've never been successful with
automated indexing myself.  For my books I've
authored the components of the index, and then
pointed to those components from within the code.

> My assumptions are that I must get rid of the
> punctuation properly, then isolate the words,
> sort them, remove stop words, and so on. To get
> started, I need a bit of help. All of the
> phrases are found in two attributes: @czech and @eng.
>
> Three questions:
> (1) I am aware from Michaelbs book that regex
> expressions may be used in the replace()
> function, but I do not know how to write that
> regex expression. I would like to remove all the
> punctuation from a phrase as follows: for
> everything except a hyphen [-], replacement
> should be with an empty string; the hyphen
> should be replaced with a single space.

Simple character removal can be done with
translate() in XSLT 1 or 2 rather than using a regular expression:

    translate($inValue,'-,#.$%',' ')

... where the first argument is your input, the
second starts with a "-" and then you put
anything else in there as characters to remove,
the third indicates the hyphen becomes a space and the rest are to be
removed.

> (2) I assume that to get rid of extra spaces (if
> any), I can use a construct like:
> normalize-space(replace(@czech, bsome regex expressionb)).

That will reduce all sequences of white-space characters to a single space.

> (3) I assume that
> tokenize(normalize-space(replace(@czech, 'some
> regex expression'))) will permit me to write out
> a list of the words found in those attributes to
> an XML document. I am not completely clear as to
> what tokenize() returns, or how to access that return.

tokenize() returns a sequence.  But the input is only a single string.

Actually, you want to turn the expression
inside-out to get a list of words from the entire
document then something along these lines should work:

distinct-values(
(//@czech)/tokenize(translate(normalize-space(.),'-,$%.#',' '))  )

That gives you a sequence of unique words.  Can
you work from that in order to do the
hyperlinking, or do you need help there as
well?  Remember you will have to do the same
translation when creating your links, so perhaps
you should have a user function:

  mark:words(.)  as  tokenize(translate(normalize-space($arg),'-,$%.#',' '))

... then use:

  (//@czech)/mark:words(.)

... then when creating your links you'll have the
function available to ensure the same tokenizing is done at the point in
time.

I hope this helps.

. . . . . . . . . . Ken


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