When I was trying to get the week number, Since the following phenomena were confirmed, the cause and countermeasure memo
import datetime
datetime.date(year=2017, month=1, day=1).isocalendar()
> (2016, 52, 7)
Why is New Year's Day 2017 2016! ??
According to the following article, Calculate week numbers in Python
ISO 8601 week number definition The week including the first Thursday is the first week. The week starts on Monday. American week number definition The week including January 1st is the first week. The week starts on Sunday.
That means.
In other words, the above result seems to be correct in the format of ISO8601.
But this time I want the result of `American` ...
I searched and found no way to change isocalendar () `` `to American `` `, so I wrote the code myself.
2020/03/27 postscript: The code was incorrect, so I fixed it.
def american_calendar(year, month, day):
#Datetime of input year.Create date type data
inp = datetime.date(year=year, month=month, day=day)
#Datetime on New Year's Day of input year.Create date type data
first = datetime.date(year=year, month=1, day=1)
#First,Calculation of the day of the week
inp_how = (inp.weekday()+1) % 7 #+1 is to change the day of the week to start on Sunday
first_how = (first.weekday()+1) % 7
#Less than,Week number calculation
#Upper left of the calendar(First sunday)Get the date
upper_left = first - datetime.timedelta(days=first_how)
#Get the week number by calculating the difference in the number of days from the base date
inp_week = (inp - upper_left).days // 7
return year, inp_week, inp_how
When you check the operation
american_calendar(year=2017, month=1, day=1)
> (2017, 0, 0)
It now returns the value you want.
that's all!
Note other than the work of a certain engineer: Calculate week number with Python Python documentation: date.isocalendar ()
Recommended Posts