Re: [xsl] Random number seed generation

[Michel Hendriksen <michel.hendriksen@xxxxxxxxx>]

Or:

 <with-param name="preliminary-seed"
  select="($preliminary-seed +
              10*string-length(
                substring-before($name-chars,substring($string,1,1))
              )
            ) mod $maximum-value"/>


I got this working now for SaxonB:

<xslt:template name="seed">
	<!-- Works with SaxonB only! -->
	<xslt:choose>
		<xslt:when test="function-available('date:new') and
function-available('date:get-time')" xmlns:date="java:java.util.Date">
			<xslt:variable name="date" select="date:new()"/>
			<xslt:value-of select="date:get-time($date)"/>
		</xslt:when>
		<xslt:otherwise>
			<!-- NOT random at all..... -->
			<xslt:variable name="time" select="current-time()" />
			<xslt:value-of select="seconds-from-time($time) + 60 *
minutes-from-time($time) + 3600 * hours-from-time($time)"/>
		</xslt:otherwise>
	</xslt:choose>
</xslt:template>

Gonna look into extensions for Saxon 9.3HE.

Michel

On Fri, Dec 10, 2010 at 1:15 PM, TW <zupftom@xxxxxxxxxxxxxx> wrote:
> There is certainly a lot of room for improvement.  My template returns
> the same number if two ids consist of the same characters in a
> different order.  Maybe multiplying with a constant in every step
> would already be a bit better:
>
> <with-param name="preliminary-seed"
>  select="3*($preliminary-seed +
>              string-length(
>                substring-before($name-chars,substring($string,1,1))
>              )
>            ) mod $maximum-value"/>
>
>
> 2010/12/10 TW <zupftom@xxxxxxxxxxxxxx>:
>> I don't know whether this would give reasonably results, but what
>> about generating a seed from the result of generate-id()?  Maybe like
>> so, calculating kind of a digit sum (based on the the order the
>> variables occur in "name-chars"):
>>
>> <template name="create-seed">
>>  <param name="string" select="generate-id(.)"/>
>>  <param name="preliminary-seed" select="0"/>
>>  <param name="maximum-value" select="100"/>
>>
>>  <variable name="name-chars"
>>
select="':ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz-.0123456789'"
/>
>>
>>  <choose>
>>    <when test="string-length($string) != 0">
>>      <call-template name="create-seed">
>>        <with-param name="string" select="substring($string,2)"/>
>>        <with-param name="preliminary-seed"
>>          select="($preliminary-seed + string-length(
>>
>> substring-before($name-chars,substring($string,1,1))
>>                                       )
>>                  ) mod $maximum-value"/>
>>        <with-param name="maximum-value" select="$maximum-value"/>
>>      </call-template>
>>    </when>
>>    <otherwise>
>>      <value-of select="$preliminary-seed"/>
>>    </otherwise>
>>  </choose>
>> </template>
>>
>>
>> Of course this only makes sense if you need at most one random number
>> per source document node (after all, the random number will be the
>> same if the seed is the same).  Or you can pass the old seed as
>> parameter "preliminary-seed" when you create a new seed.
>>
>> Thomas W.