Thanks. @billylanchantin the mask function helped alot. Sorry, that I was not able find it.
The calendar week is somewhat more complex, because it first week of the year, might partly be counted as the last week of the year before. I had to look it up. Normally I would expect it to be a part of the date(time) library
wikipedia states the ISO week date computes as:
Algorithm
- Subtract the weekday number from the ordinal day of the year.
- Add 10.
- Divide by 7, discard the remainder.
- If the week number thus obtained equals 0, it means that the given date belongs to the preceding (week-based) year.
- If a week number of 53 is obtained, one must check that the date is not actually in week 1 of the following year.
The edge cases below, Is what I meant and makes me wonder, whether I really understand these.
