Grouping by Year, Month, and Week Number

[Bryce_Schmidt]

Hi, I’m creating a running list of records (in this case, social media posts) and I’ve organized them by year, then by month, and then by week. To do this, I assigned format specifiers to each date with formulas. For example, 2019 is “2019”, January is “1 January,” February is “2 February,” etc. Weeks are assigned the same way – the first week of January is “1,” the last week of December is “52.”

However, I ran into trouble with a new grouped view (“Posts by Month”). I grouped these records by year, month, and week. Everything displays as it should except the last few days of December. 12/29/2019 through 12/31/2019 disappear. They are technically part of week 1 in 2020, but aren’t displaying because they are still part of the year 2019.

Is there way to force Airtable to recognize these last few days in December are part of 2019 and to show up in this grouped view? Perhaps as Week 53 in 2019?

[Elias_Gomez_Sai]

I think that’s a bug, the last day of a year should be on the week 53 (or even 54 on leap years). A year has 52 full weeks and an extra day, so the last day always falls on the 53th week.

[Bryce_Schmidt]

Interesting. I’ll note that for Airtable’s support team. Thanks for pointing that out.

[drassi]

If you want to group correctly like this, you need to use the ISO Week Year instead of your Publish Date year directly. Change your “Year” column to DATETIME_FORMAT({Publish Date},‘GGGG’). Since 12/30/2019 falls in the ISO week year 2020 and you are using ISO week numbers, you need the year column to return 2020 for 12/30/2019.

This isn’t a bug, it’s just unexpected behavior of date math, which is incredibly unintuitive. You can’t combine ISO week numbers with regular years, you have to match them with ISO week years.

[Bryce_Schmidt]

Hey, thanks for your response. This almost got me where I’d like the table to be, but there are a few hiccups. After changing the “Year” column to Week year (ISO) and “Week #” column to Week of the year (ISO), 12/29/2019 was added to the appropriate spot in December.

But now 12/30/2019 and 12/31/2019 have moved to their own grouping in 2020, and 12/31/2018 is its own group in December of 2019. Any thoughts on how to fix this? Thanks.

[drassi]

Hmm, ok, well this is being caused by the same class of problem we solved with the the year formula, except that now the problem is with the month part of the grouping—you’re currently combining the gregorian month with the ISO year & week. The simplest way to fix is to group using some different measure, e.g. using quarters instead (Q1=weeks 1-13, etc.) but if you truly need to group by month, you’ll have to figure out how to map ISO weeks back to some type of ISO month.

I can’t quickly figure out how to determine the first day of an ISO year in airtable… any formula experts have ideas on how to do that? Paging @W_Vann_Hall… If you were able to somehow compute the first day of the ISO year [DAY1], then you might be able to do something like MONTH(DATEADD(DAY1, {ISO week number}, ‘weeks’))

See also https://en.wikipedia.org/wiki/ISO_week_date#Weeks_per_month for a little background on this mapping problem.

[Bryce_Schmidt]

Hey, thanks so much for your input, @drassi! I was looking up ISO information on months and saw that same thing; where months are not standardized or defined.

If I could compute every day in a year (DDD) as a number (For example, January 1 = 1, December 31 = 365), and then group by days inside of each month, that could potentially solve my issue as well, I think.

For example, inside of January, days are grouped by 1-7, 8-14, 15-21, 22-28, and 29-31. Is that possible without getting into any crazy complex ISO formulas?

Really my end goal here is to just have months broken up into easily distinguishable chunks of days in a grouped view. Thanks again for your thoughts.

[drassi]

Ah, hey think I found an iso month solution, if you want to go that path. It’s based on the fact that Jan 4 is always in ISO Week 1, which I realized after reading the wiki entry again.

MONTH(DATEADD(DATETIME_PARSE({ISOYear}&"-01-04"),{ISOWeek}-1,‘week’))

That will sort 12/30/2019 & 12/31/2019 into ISO week 1 grouping of January 2020.

Also yes, of course you can split up using Gregorian months based on day of the month instead of ISO week, but I figured your workflow made more sense splitting up each Monday-Sunday week.

[Bryce_Schmidt]

Thanks! Appreciate you thinking through this. However, any chance you’d know how to work through the error I’m receiving now?

For reference, I’ve changed the names of my Year and Week fields to correspond to what you have. Here are their formulas currently:

ISOYear
DATETIME_FORMAT({Publish Date}, 'GGGG')

Month
MONTH( {Publish Date} ) & " " & DATETIME_FORMAT( DATETIME_PARSE( MONTH( {Publish Date} )&'', 'M' ), 'MMMM' )

ISOWeek
DATETIME_FORMAT({Publish Date},'W')

(I don’t think I’ll actually need the Month field as it is currently, but I included it here just in case.) Appreciate any help you can give.

[drassi]

I think the forum software might have converted the straight single quotes 'week' to angled single quotes ‘week’, I didn’t type them in a code block. See if fixing that back to straight single quotes helps