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[英]How to get week start dates and week number of each week in a year considering start day of the week is Monday in python?
[英]Get week number with week start day different than monday - Python
我有一個帶有日期列的數據集。 我想獲取與每個日期相關的周數。 我知道我可以使用:
x['date'].isocalendar()[1]
但它給了我開始日 = 星期一的周數。 雖然我需要一周從星期五開始。
你建議我怎么做?
“ ISO 標准”和“您想要的”部分是為了闡明您的需求。
您可以將代碼復制粘貼到“解決方案”部分,看看結果是否是您想要的。
定義
Python 標准庫datetime
結果
>>> datetime(2020, 1, 1).isocalendar()
(2020, 1, 3) # The 3rd day of the 1st week in 2020
>>> datetime(2019, 12, 31).isocalendar()
(2020, 1, 2) # The 2nd day of the 1st week in 2020
>>> datetime(2019, 1, 1).isocalendar()
(2019, 1, 2)
>>> datetime(2017, 1, 1).isocalendar()
(2016, 52, 7)
>>> datetime(2016, 12, 26).isocalendar()
(2016, 52, 1)
>>> datetime(2015, 12, 31).isocalendar()
(2015, 53, 4)
>>> datetime(2016, 1, 1).isocalendar()
(2015, 53, 5)
日歷草圖
# Mo Tu Wd Th Fr Sa Sn
# [2019-52w] DEC/ 23 24 25 26 27 28 29 /DEC
# [2020-1w] DEC/ 30 31 1 2 3 4 5 /JAN
# [2019-1w] DEC/ 31 1 2 3 4 5 6 /JAN
# [2016-52w] DEC/ 26 27 28 29 30 31 1 /JAN
# [2015-53w] DEC/ 28 29 30 31 1 2 3 /JAN
# [2016-1w] JAN/ 4 5 6 7 8 9 10 /JAN
定義
日歷草圖
# Fr Sa Sn. Mo Tu Wd Th
# [2019-51w] DEC/ 20 21 22. 23 24 25 26 /DEC
# [2019-52w] DEC/ 27 28 29. 30 31 1 2 /JAN
# [2020-1w] JAN/ 3 4 5. 6 7 8 9 /JAN
# [2018-53w] DEC/ 28 29 30. 31 1 2 3 /JAN
# [2019-1w] JAN/ 4 5 6. 7 8 9 10 /JAN
# [2016-52w] DEC/ 23 24 25. 26 27 28 29 /DEC
# [2017-1w] DEC/ 30 31 1. 2 3 4 5 /JAN
# [2015-52w] DEC/ 25 26 27. 28 29 30 31 /DEC
# [2016-1w] JAN/ 1 2 3. 4 5 6 7 /JAN
from datetime import datetime, timedelta
from enum import IntEnum
WEEKDAY = IntEnum('WEEKDAY', 'MON TUE WED THU FRI SAT SUN', start=1)
class CustomizedCalendar:
def __init__(self, start_weekday, indicator_weekday=None):
self.start_weekday = start_weekday
self.indicator_delta = 3 if not (indicator_weekday) else (indicator_weekday - start_weekday) % 7
def get_week_start(self, date):
delta = date.isoweekday() - self.start_weekday
return date - timedelta(days=delta % 7)
def get_week_indicator(self, date):
week_start = self.get_week_start(date)
return week_start + timedelta(days=self.indicator_delta)
def get_first_week(self, year):
indicator_date = self.get_week_indicator(datetime(year, 1, 1))
if indicator_date.year == year: # The date "year.1.1" is on 1st week.
return self.get_week_start(datetime(year, 1, 1))
else: # The date "year.1.1" is on the last week of "year-1".
return self.get_week_start(datetime(year, 1, 8))
def calculate(self, date):
year = self.get_week_indicator(date).year
first_date_of_first_week = self.get_first_week(year)
diff_days = (date - first_date_of_first_week).days
return year, (diff_days // 7 + 1), (diff_days % 7 + 1)
if __name__ == '__main__':
# Use like this:
my_calendar = CustomizedCalendar(start_weekday=WEEKDAY.FRI, indicator_weekday=WEEKDAY.MON)
print(my_calendar.calculate(datetime(2020, 1, 2)))
我們可以簡單地使用原始 ISO 設置初始化CustomizedCalendar
,並驗證結果是否與原始isocalendar()
的結果相同。
my_calendar = CustomizedCalendar(start_weekday=WEEKDAY.MON)
s = datetime(2019, 12, 19)
for delta in range(20):
print my_calendar.calculate(s) == s.isocalendar()
s += timedelta(days=1)
這是最小的邏輯:
你只需要在星期一增加 3 天就可以到星期四。 只需將天數添加到星期一並致電 ISO Weeknumber。 你會得到轉移后的周數。
from datetime import datetime, timedelta
x = datetime(2020, 1, 2) # this is Thursday and week 1 in ISO calendar; should be 1 in custom calendar w/ week starting Thu
y = datetime(2020, 1, 3) # this is Friday and week 1 in ISO calendar; should be 2 in custom calendar
print(x)
print(y)
def weeknum(dt):
return dt.isocalendar()[1]
def myweeknum(dt):
offsetdt = dt + timedelta(days=3); # you add 3 days to Mon to get to Thu
return weeknum(offsetdt);
print(weeknum(x));
print(myweeknum(x));
print(weeknum(y));
print(myweeknum(y));
輸出:
2020-01-02 00:00:00
2020-01-03 00:00:00
1
1
1
2
從下面復制函數,然后weeknumber(2020, 8, 21, 'Tuesday')
將為您提供 2020 年 8 月 21 日所在的星期數,星期數從Tuesday
開始,2020 年第一個Tuesday
之前的天數將有星期數字0
。
# necessary imports
from datetime import date, timedelta
import time
您可以將此答案(依賴於此答案)用於問題如何使用 Python 選擇一年中的所有星期日? 獲取指定年份中的所有星期一、星期二、星期三、...星期日。
一個輔助函數:
def weeknum(dayname):
if dayname == 'Monday': return 0
if dayname == 'Tuesday': return 1
if dayname == 'Wednesday':return 2
if dayname == 'Thursday': return 3
if dayname == 'Friday': return 4
if dayname == 'Saturday': return 5
if dayname == 'Sunday': return 6
或者,(使用這個):
def weeknum(dayname):
return time.strptime('Sunday', "%A").tm_wday
我們將要使用的主要功能:
def alldays(year, whichDayYouWant):
d = date(year, 1, 1)
d += timedelta(days = (weeknum(whichDayYouWant) - d.weekday()) % 7)
while d.year == year:
yield d
d += timedelta(days = 7)
現在要獲取給定日期的周數,請執行以下操作:
def weeknumber(year, month, day, weekstartsonthisday):
specificdays = [d for d in alldays(year, weekstartsonthisday)]
return len([specificday for specificday in specificdays if specificday <= datetime.date(year,month,day)])
specificdays
是一年中datetime.date
對象的列表,與weekstartsonthisday
是同一工作日。 例如, [d for d in alldays(2020,'Tuesday')]
開頭是這樣的:
[datetime.date(2020, 1, 7),
datetime.date(2020, 1, 14),
datetime.date(2020, 1, 21),
datetime.date(2020, 1, 28),
datetime.date(2020, 2, 4),
...
提醒一下,2020 年是這樣開始的:
該列表[specificday for specificday in specificdays if specificday <= datetime.date(year,month,day)]
將包含列表specificday
S(即星期一,星期二,...,無論你指定),即發生在某一年在你約會之前。 這個len()會給我們一周的數字。 一年中第一個specificday
日之前的天數將在0
周內。
幾個例子:
weeknumber(2020,1,1,'Tuesday')
返回: 0
weeknumber(2020,1,6,'Tuesday')
返回: 0
weeknumber(2020,1,7,'Tuesday')
返回: 1
weeknumber(2020,12,31,'Tuesday')
返回: 52
weeknumber(2020,1,1,'Wednesday')
返回: 1
看起來不錯。
如果您希望每個日期的年份恰好是日期本身的年份,那么還有另一種形式的周定義,如下所示。
# Mo Tu Wd Th Fr Sa Sn
# [2019-52w] DEC/ 23 24 25 26 27 28 29
# [2019-53w] DEC/ 30 31
# [2020-1w] JAN/ 1 2 3 4 5
# [2020-2w] JAN/ 6 7 8 9 10 11 12
# [2018-53w] DEC/ 31
# [2019-1w] JAN/ 1 2 3 4 5 6
# Fr Sa Sn. Mo Tu Wd Th
# [2019-53w] DEC/ 27 28 29. 30 31
# [2020-1w] JAN/ 1 2
# [2020-2w] JAN/ 3 4 5. 6 7 8 9
# [2018-53w] DEC/ 28 29 30. 31
# [2019-1w] JAN/ 1 2 3
# [2019-2w] JAN/ 4 5 6. 7 8 9 10
from datetime import datetime, timedelta
from enum import IntEnum
WEEKDAY = IntEnum('WEEKDAY', 'MON TUE WED THU FRI SAT SUN', start=1)
def get_week_number(start, date):
year_start = datetime(date.year, 1, 1) - timedelta(days=(datetime(date.year, 1, 1).isoweekday() - start) % 7)
return date.year, (date-year_start).days // 7 + 1, (date-year_start).days % 7 + 1
if __name__ == '__main__':
# usage:
print(get_week_number(WEEKDAY.FRI, datetime(2018, 12, 19)))
聚會有點晚了,這是我們解決的方法
def get_week(date, weekday_start):
# Number of days since day 1 of the year. First day is day 0.
number_of_days = date.timetuple().tm_yday - 1
# Get the first day of the week in int. Monday is 0, Tuesday is 1, etc.
first_day_of_week = time.strptime(weekday_start if weekday_start else 'MONDAY', "%A").tm_wday
# Get the first day of the year. isoweekday considers Monday as 1 and Sunday as 2, thus why -1.
first_day_of_year = (datetime(date.year, 1, 1).isoweekday()) - 1
# Get the week number
return (number_of_days + abs(first_day_of_week - first_day_of_year)) // 7 + 1
我們將一周的第一部分視為第 1 周。這意味着如果一年從星期二開始,星期一設置為 weekday_start,那么第一周將只有 6 天。
weekday_start 是一個將 MONDAY、TUESDAY、WEDNESDAY 等作為輸入的字符串。
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