On 06/12/13 16:09, Alexander Dutton wrote:
Hi Ewa,
On 06/12/13 16:03, Ewa Szwed wrote:
Got it!
Done:
* BIND(str(floor(fn:days-from-duration(?date_of_death - ?date_of_birth)
/ 365)) as ?age_at_death)*
Careful; that'll only get you the days component¹. Even if it did what
you were hoping for, you'll end up with off-by-one errors if they die
close to their birthday due to the cumulative effects of leap years.
You probably want:
BIND(fn:years-from-duration(?date_of_death - ?date_of_birth) AS
?age_at_death)
You are right to worry.
There are two kinds of (totally order) durations:
xsd:yearMonthDuration
xsd:dayTimeDuration
you can't mix them (months have variable number of days)
The difference of two xsd:dates is a number of day so the duration is of
the dayTimeDuration which does not have a year component.
fn:years-from-duration is an accessor - it's not calculating the number
of years because it can't as without a timeframe, you don't know about
leap years.
So ?date_of_death - ?date_of_birth is a number of days and /365 is about
the best estimate you can do without grounds the calculation in a fixed
timeframe.
I may have got this wrong, but in implementation ARQ converts to
milliseconds and then uses Java's newDuration(long milliSeconds) which
returns a large day component xsd:Duration, no years or months.
Andy
Best regards,
Alex
¹ <http://www.w3.org/TR/xpath-functions/#func-days-from-duration>
