Re: [xsl] Getting years from duration

[Martin Holmes <mholmes@xxxxxxx>]

We only wanted years, but a plain subtraction won't do, as others have 
noted; you need to check whether to subtract a year from the result or 
not, depending on the times of year of the births and deaths. So:

Born 1950 December 31
Died 2000 January 1

The plain subtraction will give you 50, but the age is actually 49 (plus 
a day). [If my math is correct at the end of a LONG day.]

Cheers,
Martin

On 13-06-08 01:42 PM, Michele R Combs wrote:
> Do you need the age down to month and day?  If not, rather than manipulating the attribute value as a date per se, can you just take the first four characters (the year) of each and do a simple subtraction?
>
> Michele
> ________________________________________
> From: Martin Holmes [mholmes@xxxxxxx]
> Sent: Friday, June 07, 2013 11:26 PM
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: [xsl] Getting years from duration
>
> We came up against what looked like a very simple XPath issue today, and
> hit a brick wall with it. Given data that looks like this:
>
>           <person role="author">
>             <persName>Milton, John</persName>
>             <birth when="1600-12-09"/>
>             <death when="1674-11-08"/>
>           </person>
>
> we want to calculate the age of the person at death. So we thought:
> subtract the death date from the birth date to get a duration, then
> extract the years from the duration:
>
>     <xsl:template match="person">
>
>       <xsl:variable name="life" select="xs:date(death/@when) -
> xs:date(birth/@when)"/>
>
>       <xsl:variable name="age" select="years-from-duration($life)"/>
>
>       <xsl:text>Age at death: </xsl:text>
>       <xsl:value-of select="$age"/>
>
>     </xsl:template>
>
>
> However, the only value we were able to get back, after trying all
> manner of permutations and casts, was zero. It appears that what comes
> back from the date subtraction (which I think uses the
> op:subtract-dates() operator) is always an xs:dayTimeDuration, and that
> cannot AFAIKS be manipulated into anything from which a year can be
> extracted.
>
> It's always possible to get the number of days and divide by 365.25, but
> it seems strange to have to do that. Given the range of date- and
> duration-related functions, I'm sure there must be some better way of
> getting the result. Does anyone know?
>
> This is using Saxon 9.4.0.6.
>
> Cheers,
> Martin
>
> .

--
Martin Holmes
University of Victoria Humanities Computing and Media Centre
(mholmes@xxxxxxx)