一周一天，一天一年

Question

我想知道你如何通过给予日，周数和年份来获得月份。

例如，如果你有这样的东西

def getmonth(day, week, year):
    # by day, week and year calculate the month
    print (month)

getmonth(28, 52, 2014)
# print 12

getmonth(13, 42, 2014)
# print 10

getmonth(6, 2, 2015)
# print 1

Answer 1

from datetime import datetime, timedelta    
def getmonth(day, week, year):
    d = datetime.strptime('%s %s 1' % (week-1, year), '%W %Y %w')

    for i in range(0, 7):
        d2 = d + timedelta(days=i)
        if d2.day == day:
            return d2.month

Answer 2

您可以使用isoweek模块执行此操作，例如第一个示例：

from isoweek import Week
w = Week(2014, 52)
candidates = [date for date in w.days() if date.day == 28]
assert len(candidates) == 1
date = candidates[0] # your answer

Answer 3

根据interjay的建议 ：

import datetime as DT

def getmonth(day, week, year):
    for month in range(1, 13):
        try:
            date = DT.datetime(year, month, day)
        except ValueError:
            continue
        iso_year, iso_weeknum, iso_weekday = date.isocalendar()
        if iso_weeknum == week:
            return date.month

print(getmonth(28, 52, 2014))
# 12

print(getmonth(13, 42, 2014))
# 10

print(getmonth(6, 2, 2015))
# 1

Answer 4

当我需要实现一些棘手的日期操作时，我正在使用python-dateutil 。

from datetime import date
from dateutil.rrule import YEARLY, rrule

def get_month(day, week, year):
    rule = rrule(YEARLY, byweekno=week, bymonthday=day, dtstart=date(year, 1, 1))
    return rule[0].month