Hi
2009/5/11 Murodullo Latifov <murodlatifov@xxxxxxxxx>:
Hi Caveman,
----- Original Message ----
From: Orvalho Joaquim Augusto <orvaquim@xxxxxxxxx>
To: dhis2-devs <dhis2-devs@xxxxxxxxxxxxxxxxxxx>
Sent: Monday, May 11, 2009 2:57:42 AM
Subject: [Dhis2-devs] weeks calculation
I could not find on dhis2 docs so I am asking:
How dhis2 calculate the weeks? The first week of a year for example.
Weekly periods are calculated based on their start date. If start date of the given week is on the previous year, end date of that period is used. Also
Saturday is used as first day of the week.
The code is here:
./dhis-api/src/main/java/org/hisp/dhis/period/WeeklyPeriodType.java
I find it a bit confusing. It seems that we try to define a week as
Saturday to Friday, and then say that as long as the endDate is in a
different year to the startDate then we are in week 1. So week 1 is
the first week in the year with a Friday in it? This doesn't sound
right. Also according to documentation on top of class, a weekly
period must have a startDate on a Monday and endDate on a Sunday.
But week numbers according to ISO8601 are equivalent to the number of
Thursdays - ie. first week in the year with a Thursday is week 1.
This is the way that, for example the javascript in the calendar.js
would calculate it. And presumably any sql week function we might
use. Also weeks would start on Monday (which agrees with our class
documentation).
So for the week of 29/12/2008 to 04/01/2009, by our calculation that
would be week 1 of 2009. And it would be week 1 by ISO 8601.
But for the week of 28/12/2009 to 3/01/2010 which is coming up, our
calculation would have this as week 1 of 2010, whereas ISO8601 would
have it as week 52 or 53 of 2010. Week 1 would be the week of
04/01/2010.
As I say - its a bit confusing.
Though perhaps in the end the actual week number doesn't matter. What
might matter most is the convention we consistently adopt and
document. Though it would be nice if our conception of week 1
coincided with the ISO8601 conception. But not so nice as to break
all the annual reports ... Do we ever exchange a week number with
another system? Do we need to be able to define this more flexibly to
accomodate different national reporting requirements which might
interpret the first week of the year differently? I haven't even
begun to think of this in terms of localised calendar systems :-)
Regards
Bob
Thank you
Caveman
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