美国大选日熊猫假日日历规则

Question

在使用Pandas Holiday类创建假日日历时，我无法确定创建美国选举日日历的正确规则。美国选举日的定义是11月第一个星期一之后的星期二，每偶数年都会发生一次。使用定义的Holiday类：

class USElectionCalendar(AbstractHolidayCalendar):
"""        
Federal Presidential  and Congressional election day.
Tuesday following the first Monday, 2 to 8 November every two even numbered years.
Election Days can only occur from November 2nd through 8th inclusive.
"""
rules = [
    Holiday("Election Day",month=11, day=2, offset=pd.DateOffset(weekday=TU(1))),
]

带有

start_date = '20160108'
end_date   = '20261231'

进入功能

def holidays_between_dates(calendar, start_date, end_date):
    cal = calendar
    dates = cal.holidays(start_date, end_date, return_name=True)
    return dates

返回

2016-11-08    Election Day
2017-11-07    Election Day
2018-11-06    Election Day
2019-11-05    Election Day
2020-11-03    Election Day
2021-11-02    Election Day
2022-11-08    Election Day
2023-11-07    Election Day
2024-11-05    Election Day
2025-11-04    Election Day
2026-11-03    Election Day

除了奇数年，一切都很好。正如本期文章中所讨论的，我尝试合并了两个偏移。向规则添加2年的偏移量

Holiday("Election Day", month=11, day=2, offset=[ pd.DateOffset(weekday=TU(1)), pd.DateOffset(years=2) ])

只需将第一次发生的事件转移到未来2年。我不确定所需的时间序列是否可行。那么问题来了：

有没有可能直接构建这个日历，或者我需要用第二个函数从Pandas日历对象中删除奇数年？

Answer 1

您可以在制定假日时使用遵守而不是偏移，并在奇数年返回None:

def election_observance(dt):
    if dt.year % 2 == 1:
        return None
    else:
        return dt + pd.DateOffset(weekday=TU(1))

class USElectionCalendar(AbstractHolidayCalendar):
    """
    Federal Presidential  and Congressional election day.
    Tuesday following the first Monday, 2 to 8 November every two even numbered years.
    Election Days can only occur from November 2nd through 8th inclusive.
    """
    rules = [
        Holiday('Election Day', month=11, day=2, observance=election_observance)
    ]

cal = USElectionCalendar()
start_date = '20160108'
end_date = '20261231'
print cal.holidays(start_date, end_date, return_name=True)

输出：

2016-11-08    Election Day
2018-11-06    Election Day
2020-11-03    Election Day
2022-11-08    Election Day
2024-11-05    Election Day
2026-11-03    Election Day
dtype: object

请注意，在构建Holiday时，您不希望同时使用偏移和遵守，并且尝试这样做会在最近的panda版本中引发异常。