Is there a better solution thant dt.weekofyear?

Question

Is there a better solution than df['weekofyear'] = df['date'].dt.weekofyear?

The problem of this solution is that, sometimes, the days after the last week of the year n but before the first week of the year n+1 are counted as week 1 and and not as week 0.

I am working with pyspark and koalas (no pandas allowed).

Here is an example:

As you can see, the first column is Date, the second one is week, the third is month and last is year.

could you show examples of some dates that suffer from this problem? — mck, Dec 24 '20 at 10:48
Date - Weekofyear - Month - Year. But the problem is only on the second column. — Ousen92i, Dec 24 '20 at 10:55
why would you want them to be week 0...? they are technically on the same week, though separated across the year. — mck, Dec 24 '20 at 11:04
Because I want to goupby(weekofyear) my data. And the problem is that for example, Week 1 tooks the real first week of 2019, but add the to it the last day of 2019 wich are counted as week 1 as well. It makes no sense. — Ousen92i, Dec 24 '20 at 11:08
ISO 'week number' is only useful when paired with the *year* of the ISO week number, which won't necessarily be the calendar year. e.g., `date -d '2019-12-31' +%G-W%V` gives `2020-W01`. If there's no way to get that year, `weekofyear` is difficult to use correctly. — Joe, Dec 24 '20 at 12:40

mck · Accepted Answer · 2020-12-24T14:37:23.330

1

Not sure if this is what you want...? I suppose you can use case when to replace the undesired values of week of year.

df['weekofyear'] = df['date'].dt.weekofyear

df2 = ks.sql("""
select
    date,
    case when weekofyear = 1 and month = 12 then 53 else weekofyear end as weekofyear,
    month,
    year
from {df}""")

edited Dec 24 '20 at 14:37

answered Dec 24 '20 at 11:18

mck

40,932
13
35
50

1

@Ousen92i I've added another way, which is more pythonic and pandas-like - see if that works for you? – mck Dec 24 '20 at 12:29
When I tried the 2nd way, I got an error : 'Series' object does not support item assignment – Ousen92i Dec 24 '20 at 13:59
@Ousen92i okay, I didn't expect it to work anyway, how about the first one? – mck Dec 24 '20 at 14:00

Is there a better solution thant dt.weekofyear?

1 Answers1