Python datetime : isocalendar, strftime('%U'), strftime('%W') (week number 추출)

 

 

 

import datetime

dt = datetime.date(2020, 12, 25)
print(dt)
iso_data = dt.isocalendar()
print(iso_data)
print(iso_data[0]) # year
print(iso_data[1]) # week number
print(iso_data[2]) # week day number

- Result
2020-12-25
(2020, 52, 5)
2020
52
5

isocalendar는 date or datetime에 대해 해당 날짜의 년도, 주차(week number), 요일(week day)을 포함한 Tuple 데이터를 반환합니다.

따라서 return된 Tuple의 index = 1인 숫자를 보면 week number를 얻을 수 있습니다.

 

참고로 반환되는 week day에 대한 숫자는 아래와 같습니다.

월요일 = 1

화요일 = 2

수요일 = 3

목요일 = 4

금요일 = 5

토요일 = 6

일요일 = 7

 

 

 

 

 

 

 

 

 

week number는 date format의 숫자에 strftime을 적용하는 방법으로도 얻을 수 있습니다.

 

총 2가지 방법이 있는데 다음과 같습니다.

date.strftime('%U') # --> 일요일부터 시작하는 기준으로 week number 계산하여 반환
date.strftime('%W') # --> 월요일부터 시작하는 기준으로 week number 계산하여 반환

 

 

 

 

 

아래는 strftime을 이용한 예시입니다.

import datetime

dt_today = datetime.date.today()
print(dt_today)

list_weekdays = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']

for i in range(21):
    date = dt_today + datetime.timedelta(days=i)

    week_number_sun_start = date.strftime('%U')
    weekday_number = date.weekday()
    weekday_name = list_weekdays[weekday_number]

    print('date = {date} / week day = {week_day} --> week number = {week_number}'\
          .format(date=date, week_day=weekday_name, week_number=week_number_sun_start))



-- Result
date = 2021-08-12 / week day = Thu --> week number = 32
date = 2021-08-13 / week day = Fri --> week number = 32
date = 2021-08-14 / week day = Sat --> week number = 32

date = 2021-08-15 / week day = Sun --> week number = 33
date = 2021-08-16 / week day = Mon --> week number = 33
date = 2021-08-17 / week day = Tue --> week number = 33
date = 2021-08-18 / week day = Wed --> week number = 33
date = 2021-08-19 / week day = Thu --> week number = 33
date = 2021-08-20 / week day = Fri --> week number = 33
date = 2021-08-21 / week day = Sat --> week number = 33

date = 2021-08-22 / week day = Sun --> week number = 34
date = 2021-08-23 / week day = Mon --> week number = 34
date = 2021-08-24 / week day = Tue --> week number = 34
date = 2021-08-25 / week day = Wed --> week number = 34
date = 2021-08-26 / week day = Thu --> week number = 34
date = 2021-08-27 / week day = Fri --> week number = 34
date = 2021-08-28 / week day = Sat --> week number = 34

date = 2021-08-29 / week day = Sun --> week number = 35
date = 2021-08-30 / week day = Mon --> week number = 35
date = 2021-08-31 / week day = Tue --> week number = 35

strftime('%U')를 사용했으므로 Sun부터 시작해서 Sat까지가 한 주로 판단되어 동일한 week number를 가지는 것을 알 수 있습니다.

 

 

 

 

 

 

 

 

 

import datetime

dt_today = datetime.date.today()
print(dt_today)

list_weekdays = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']

for i in range(21):
    date = dt_today + datetime.timedelta(days=i)

    week_number_sun_start = date.strftime('%W')
    weekday_number = date.weekday()
    weekday_name = list_weekdays[weekday_number]

    print('date = {date} / week day = {week_day} --> week number = {week_number}'\
          .format(date=date, week_day=weekday_name, week_number=week_number_sun_start))



-- Result
date = 2021-08-12 / week day = Thu --> week number = 32
date = 2021-08-13 / week day = Fri --> week number = 32
date = 2021-08-14 / week day = Sat --> week number = 32
date = 2021-08-15 / week day = Sun --> week number = 32

date = 2021-08-16 / week day = Mon --> week number = 33
date = 2021-08-17 / week day = Tue --> week number = 33
date = 2021-08-18 / week day = Wed --> week number = 33
date = 2021-08-19 / week day = Thu --> week number = 33
date = 2021-08-20 / week day = Fri --> week number = 33
date = 2021-08-21 / week day = Sat --> week number = 33
date = 2021-08-22 / week day = Sun --> week number = 33

date = 2021-08-23 / week day = Mon --> week number = 34
date = 2021-08-24 / week day = Tue --> week number = 34
date = 2021-08-25 / week day = Wed --> week number = 34
date = 2021-08-26 / week day = Thu --> week number = 34
date = 2021-08-27 / week day = Fri --> week number = 34
date = 2021-08-28 / week day = Sat --> week number = 34
date = 2021-08-29 / week day = Sun --> week number = 34

date = 2021-08-30 / week day = Mon --> week number = 35
date = 2021-08-31 / week day = Tue --> week number = 35
date = 2021-09-01 / week day = Wed --> week number = 35

strftime('%W')를 사용했으므로 Mon부터 시작해서 Sun까지가 한 주로 판단되어 동일한 week number를 가지는 것을 알 수 있습니다.