dayofyear is not great when going into a new year

[Richard Damon]

On 1/5/21 8:02 PM, Mats Wichmann wrote:
> On 1/5/21 4:04 PM, Chris Angelico wrote:
>> On Wed, Jan 6, 2021 at 10:01 AM Eli the Bearded
>> <*@eli.users.panix.com> wrote:
>>>
>>> In comp.lang.python, Chris Angelico  <rosuav at gmail.com> wrote:
>>>> There are multiple definitions for "day of year", depending on how you
>>>> want to handle certain oddities. The simplest is to identify Jan 1st
>>>> as 1, Jan 2nd as 2, etc, to Dec 31st as either 365 or 366; but some
>>>> libraries will define the year as starting with the week that contains
>>>> the Thursday, or something, and then will define days of year
>>>> accordingly.
>>>
>>> That sounds like some weird off-shoot of the ISO-8601 calendar. That
>>> document primarily concerns itself with weeks. Week 1 of a year is the
>>> first week with a Thursday in it. The last week of a year will be
>>> either
>>> 52 or 53, and you can have things like days in January belonging to the
>>> week of the previous year.
>>
>> The "weird off-shoot" part is probably a result of me misremembering
>> things, so don't read too much into the details :) I just remember
>> coming across something that numbered days within a year in a way that
>> was consistent with the way that it numbered weeks, which would indeed
>> have been based on the ISO 8601 week numbering. Not 100% sure of the
>> exact details.
>
> "workweeks" has always been fun, ISO standard or not, there's been a
> variation for ages since people don't seem to always follow ISO for
> that.  I spent over a decade at a place that lived and died by their
> WorkWeek references ("due WW22" or the like would appear in every
> status report ever written, and there were zillions of those) - and it
> didn't agree with ISO on whether WW1 was the week that contained Jan 1
> or whether it was the week that followed the previous year's last
> workweek. After all, those few days can't actually belong to two
> different workweeks, now can they?  :)
>
> (that was not a good memory you guys brought back :) )

I'm reminded of a video made describing 'ISO Weeks' that was put out on
Dec 30, 2019, which was the first day of the ISO week bsed 2020, and he
ended it with a comment that if 2019 wasn't going so well, you could
always just use ISO to get an early start on 2020.

Apparently a lot of people were getting this recommended a number of
months later, and people were commenting how that line just was not
aging well. And we couldn't use that te get out of 2020, as 2020 is a
long year, and ISO 2021 didn't start until Jan 4th.

-- 
Richard Damon