topic Extract week number from Date and Time field using Field Calculator in ArcPro in ArcGIS Pro Questions

Extract week number from Date and Time field using Field Calculator in ArcPro

RachelS — Tue, 11 Mar 2025 11:34:03 GMT

Hi,

I'm hoping someone can help me to extract the week number from a date and time field using Field Calculator in ArcPro. I've tried a few codes I've found online but nothing is working.

My layer is called oyster, my fieldnames are surveydate and weeknumber.

Thanks

Rachel

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

DanielFox1 — Tue, 11 Mar 2025 11:56:42 GMT

Hi @RachelS

My reading of your query is you need to calculate the week number of the data you have, I found the following link which might

https://developers.arcgis.com/arcade/function-reference/date_functions/#isoweek

This example from ArcGIS Survey 123 might also help

https://community.esri.com/t5/arcgis-survey123-questions/how-to-calculate-the-week-number-of-a-date/td-p/1217824

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

DanPatterson — Tue, 11 Mar 2025 12:51:08 GMT

or via python builtins. You just need to add an integer field to get the week number

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

JoshuaBixby — Tue, 11 Mar 2025 13:19:34 GMT

If you shared some of the code samples you tried along with the errors or unexpected results, people could comment on why the code samples aren't working for you. Also, sharing either example or sample data along with expected results helps people give better answers.

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

RachelS — Tue, 11 Mar 2025 14:02:49 GMT

Hi @DanPatterson
Yes, this is the code I tried but I got the error message below.
My surveydate field is type 'Date' like 03/12/2024 16:44:00.000.
I thought it was because my week field was a string but when I created one that was an integer 'Long', I still get the error below.

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

RachelS — Tue, 11 Mar 2025 14:05:26 GMT

Hi @JoshuaBixby
The code I tried is in Dan's reply above but I get the error in the screenshot posted above.
The sample date is 03/12/2024 16:44:00.000 and in another field called week I'd just like to get it return 49.

I've 2000 of these records to update.

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

RachelS — Tue, 11 Mar 2025 14:07:28 GMT

Hi @DanielFox1

I've tried the the isocalender but I'm getting an error posted in the reply to Dan,
The example from Survey123, I've implemented this in my Survey123 form so this won't be an issue going forward. I just have 2,000 records from the last few years I'm trying to get updated.

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

KenBuja — Tue, 11 Mar 2025 15:00:10 GMT

You can use the Arcade script

ISOWeek($feature.surveydate)

This is how it would look in the Field Calculator (with my data)

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

RachelS — Tue, 11 Mar 2025 15:58:45 GMT

That's it, works perfect, although I didn't have to put ISO in front of Week.

Thank you!

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

DanPatterson — Tue, 11 Mar 2025 16:07:52 GMT

you date field was a string that was the problem, if you try it with a true date field as input and the output field (week) as integer (long) it should work, as in my example

And you can use python outside of the esri environment 😉

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

KenBuja — Tue, 11 Mar 2025 16:08:32 GMT

There's difference between the two. Week returns a value where the first week is 0 while ISOWeek returns a value where the first week is 1. Take a look at the difference using your example date (remember that month is zero-based)

Re: Extract week number from Date and Time field using Field Calculator in ArcPro

RachelS — Wed, 12 Mar 2025 11:35:54 GMT

Hi @DanPatterson

That's interesting, how do I get the field to be a true date field? The properties of the field in ArcPro is 'Date' type.

I even created a new field in ArcPro as type Date, copied over the data and ran it but it still did the same.