Question

我需要在Python中获得每个月的第二个星期五。

我写了下面的函数来演示我需要的东西。但是，我想知道是否有更优雅的方式使用Pandas的date_range函数和适当的偏移量。

def second_friday_of_month_date_range( start, end ):
    dr = pd.date_range( start, end, freq='MS' )

    first_weekday_of_month_to_2nd_friday_of_month = np.array( [ 12, 11, 10, 9, 8, 14, 13 ], dtype=int )
    wd                                            = first_weekday_of_month_to_2nd_friday_of_month[ dr.weekday ]
    offsets                                       = [ datetime.timedelta( days=int(x)-1 ) for x in wd ]
    dts                                           = [d+o for d, o in zip( dr, offsets)]
    return pd.DatetimeIndex( dts )

import pandas as pd
import datetime
d0 = datetime.datetime(2016,1,1)
d1 = datetime.datetime(2017,1,1)
dr = second_friday_of_month_date_range( d0, d1 )
print( dr )

>> DatetimeIndex(['2016-01-08', '2016-02-12', '2016-03-11', '2016-04-08',
               '2016-05-13', '2016-06-10', '2016-07-08', '2016-08-12',
               '2016-09-09', '2016-10-14', '2016-11-11', '2016-12-09',
               '2017-01-13'],
              dtype='datetime64[ns]', freq=None, tz=None)

Answer 1

您可以在freq='WOM-2FRI'中设置pd.date_range（“一周，第二个星期五”）轻松完成此操作。因此，为了获得预期的输出，您可以写：

pd.date_range('2016-01-01', freq='WOM-2FRI', periods=13)

输出结果为：

DatetimeIndex(['2016-01-08', '2016-02-12', '2016-03-11', '2016-04-08',
               '2016-05-13', '2016-06-10', '2016-07-08', '2016-08-12',
               '2016-09-09', '2016-10-14', '2016-11-11', '2016-12-09',
               '2017-01-13'],
              dtype='datetime64[ns]', freq='WOM-2FRI')

Answer 2

尝试this aproach：

import dateutil as du
import pandas as pd

start=du.parser.parse('2016-01-01')

rr = du.rrule.rrule(du.rrule.MONTHLY,
                    byweekday=du.relativedelta.FR(2),
                    dtstart=start,
                    count=12)

dates = [pd.to_datetime(d) for d in rr]

输出：

In [33]: dates
Out[33]:
[Timestamp('2016-01-08 00:00:00'),
 Timestamp('2016-02-12 00:00:00'),
 Timestamp('2016-03-11 00:00:00'),
 Timestamp('2016-04-08 00:00:00'),
 Timestamp('2016-05-13 00:00:00'),
 Timestamp('2016-06-10 00:00:00'),
 Timestamp('2016-07-08 00:00:00'),
 Timestamp('2016-08-12 00:00:00'),
 Timestamp('2016-09-09 00:00:00'),
 Timestamp('2016-10-14 00:00:00'),
 Timestamp('2016-11-11 00:00:00'),
 Timestamp('2016-12-09 00:00:00')]

如何获得每个月的第二个星期五的日期范围？

2 个答案: