I recently used the EXSLT random number extension in Saxon to generate
random numbers within a range from 0 to say 20,000 in order to randomly
select items from a document (in my case, words from the standard Linux
words spellcheck dictionary, made into a simple XML document for ease of
XSLT access).
This was the relevant code I used:
<xsl:variable name="words" as="document-node()"
select="document('data-files/words.xml')"/>
<xsl:variable name="wordCount" as="xs:integer"
select="count($words/*/*)"/>
<xsl:variable name="seed"
select="(seconds-from-dateTime(current-dateTime()) + .) * 1000"
as="xs:double"/>
<xsl:variable name="wordIndex" as="xs:integer"
select="if ($doRandom)
then xs:integer(exslt-random:random-sequence(1, $seed) *
$wordCount)
else ."
/>
The seed construction is a little weak but sufficient for my needs since I
wouldn't be running the process twice within the same second.
Of course, being able to get a truly random seed would be nice but
pseudo-random is usually good enough.
Cheers,
Eliot
—————
Eliot Kimber, Owner
Contrext, LLC
http://contrext.com
On 5/6/14, 11:54 AM, "Michael Kay mike(_at_)saxonica(_dot_)com"
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:
The W3C WGs are looking at the idea of introducing a random-number
function of some kind in XPath 3.1. The challenge of course is making
this both usable and a pure function with no side-effects. We have
various design ideas which we need to test against requirements.
If you have any applications that use or need such a function, please
could I have a brief description of the way it uses random numbers, e.g.
just wanting a single random number, a random permutation of 52 integers,
an arbitrary sequence of random numebrs for test data generation, etc.
If you're currently using the EXSLT random-sequence() function, please
share your experience with it.
Michael Kay
Saxonica
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