If you regard a day as ending precisely at midnight, the convention is the
same for both archive intervals and for a day: exclusive on the left,
inclusive on the right.

A five-minute archive interval timestamped 11:35 includes all data from
just after 11:30 to precisely 11:35. In a similar manner, a day timestamped
1-Feb-2010 includes all data from just after 31-Jan 00:00 to precisely
1-Feb 00:00.

On Tue, Feb 28, 2023 at 9:53 AM Karen K <[email protected]> wrote:

> May be it worth mentioning the background that the archive interval is
> open at the left end (start time) and closed at the right end (end time).
> That is not uncommon. It is a widely used design. That is because it is the
> only way to combine values that summarize the archive interval with actual
> readings. Unfortunately the day is counted the other way round: It starts
> at 00:00 and ends right before 00:00 the next day.
>
> Tom Keffer schrieb am Dienstag, 28. Februar 2023 um 18:02:30 UTC+1:
>
>> I assume you are referring to the tags $month.start and $month.end, the
>> start and stop of the interval $month. See
>> http://www.weewx.com/docs/customizing.htm#Start,_end,_and_dateTime
>>
>> Using the example from the Customizing Guide, if $month.end returned
>> 31-Jan-2010, what time should it be? It can't be 00:00: we would be missing
>> the whole day 31-Jan-2010. It also can't be 24:00: no such time exists.
>>
>> So, it must be 1-Feb-2010 at midnight. The month runs right up to the
>> instant the clock turns over into February.
>>
>> Now I recognize that when one is running a report that works in units of
>> days, not instants of time, you might want to represent the end of the
>> month as being 31-Jan-2010 (no time) and not 1-Feb-2010 00:00.
>>
>> Thinking out loud here, we could create tags such as:
>>
>> $week.last_day
>> $month.last_day
>> $year.last_day
>>
>> but I'm not sure what they would return. While the tag $month.end
>> returns a ValueHelper that holds a unix epoch time internally, that's
>> not going to work for $month.last_day, because it will print 31-Jan-2010
>> 00:00 --- not what we want. The user would have to always remember to
>> custom format it to show only days --- no time. Something like
>> $month.last_day.format("%d-%b-%Y"). That feels wrong.
>>
>> Alternatively, $month.last_day could return a Julian Day or a Python
>> datetime.date object. I'd have to think about it.
>>
>> If you're really stuck, you can always custom format the end of the month
>> like this:
>>
>> #from time import strftime, localtime
>> <p>Month ends at $strftime("%d-%b-%Y", $localtime($month.end.raw - 1
>> ))</p>
>>
>>
>> Note the "- 1". That shoves the time into the previous day. The results
>> will be 31-Jan-2010.
>>
>>
>>
>>
>> On Tue, Feb 28, 2023 at 5:32 AM Marcus Zurhorst <[email protected]>
>> wrote:
>>
>>> Hi all.
>>>
>>> *I am wondering why the website tells me that the intervall for the
>>> current months spans "01.02.2023 - 01.03.2023"? -- Same for year, which
>>> goes to Jan 1, 2024 actually.*
>>>
>>>
>>> *Whilst being a minor glitch, I do not understand this design decision
>>> at all since it is uncommon. Can somebody explain which this is done this
>>> way? Plus, is this even theme-related, or would that be a discussion for
>>> the weewx project itself?*
>>>
>>> I have initially raised this question on Github [1
>>> <https://github.com/Daveiano/weewx-wdc/discussions/115>] with regard to
>>> the weewx-wdc theme.
>>> Daveiano first thought that this would be specific to his theme. But
>>> when looking into this, he actually found out that this would be related to
>>> weewx itself.
>>>
>>> Can somebody please elaborate why this is designed like this?
>>>
>>> Thanks a lot.
>>>
>>> Best regards,
>>>   Marcus
>>>
>>>
>>> [1]  https://github.com/Daveiano/weewx-wdc/discussions/115
>>>
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