美国大选日熊猫假期规则

Question

在使用Pandas假日类创建假日日历时，我无法确定为美国选举日创建日历的适当规则。美国选举日的定义是11月的第一个星期一之后的星期二，每一年都有偶数年发生。使用定义的假日类：

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))),
]

使用

start_date = '20160108'
end_date   = '20261231'

转成功能

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。我已经尝试合并了两个偏移，在这个问题中已经讨论过了。在规则中增加2年的抵消

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情移到未来2年。我不确定期望的时间序列是否可能。因此，关于这个问题：

是否可以直接构造这个日历，或者我是否需要用第二个函数从Pandas日历对象中删除奇数年份？

Answer 1

你可以在放假时使用纪念而不是抵消，并让它在奇数年内不返回：

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，在构建假日时，您不希望同时使用偏移量和纪念值，这样做会在最近的熊猫版本中引发一个例外。