如何從PandasUSFederalHolidayCalendar中洗掉特定假期？

我正在嘗試從pandas.tseries.holiday.USFederalHolidayCalendar.

這似乎是可能的，作為一次性操作，

from pandas.tseries.holiday import USFederalHolidayCalendar
cal = USFederalHolidayCalendar()
cal = cal.rules.pop(6)

但是，如果此代碼位于重復呼叫（在回圈中）以生成多個獨立輸出的函式中，則會出現以下錯誤：

IndexError: pop index out of range

它給我的印象是物件保持在其初始加載狀態，隨著回圈的進行，它會在索引 6 處彈出假期，直到它們消失，然后拋出錯誤。

我嘗試通過重新加載importlib.reload無濟于事。

知道我做錯了什么嗎？

uj5u.com熱心網友回復：

這里的問題是這rules是一個類屬性（物件串列）。請參閱從此處獲取的代碼：

class USFederalHolidayCalendar(AbstractHolidayCalendar):
    """
    US Federal Government Holiday Calendar based on rules specified by:
    https://www.opm.gov/policy-data-oversight/
       snow-dismissal-procedures/federal-holidays/
    """

    rules = [
        Holiday("New Years Day", month=1, day=1, observance=nearest_workday),
        USMartinLutherKingJr,
        USPresidentsDay,
        USMemorialDay,
        Holiday("July 4th", month=7, day=4, observance=nearest_workday),
        USLaborDay,
        USColumbusDay,
        Holiday("Veterans Day", month=11, day=11, observance=nearest_workday),
        USThanksgivingDay,
        Holiday("Christmas", month=12, day=25, observance=nearest_workday),
    ]

由于屬性是在類上定義的，因此只參考了一個底層串列，因此如果對該類的不同實體的操作都嘗試編輯串列，那么您將有一些不需要的行為。這是一個示例，顯示了正在發生的事情：

>>> class A:
...     rules = [0,1,2]
... 
>>> a1 = A()
>>> a2 = A()
>>> a1.rules.pop()
2
>>> a1.rules.pop()
1
>>> a2.rules.pop()
0
>>> a2.rules.pop()
IndexError: pop from empty list
>>> a3 = A()
>>> a3.rules
[]

另外，python中的每個模塊只匯入一次

uj5u.com熱心網友回復：

# Import your library
from pandas.tseries.holiday import USFederalHolidayCalendar

# Get an id of 'columbus' in 'rules' list
columbus_index = USFederalHolidayCalendar().rules.index([i for i in USFederalHolidayCalendar().rules if 'Columbus' in str(i)][0])

# Create your own class, inherit 'USFederalHolidayCalendar'
class USFederalHolidayCalendar(USFederalHolidayCalendar):
    # Exclude 'columbus' entry
    rules = USFederalHolidayCalendar().rules[:columbus_index]   USFederalHolidayCalendar().rules[columbus_index 1:]

# Create an object from your class
cal = USFederalHolidayCalendar()
print(cal.rules)

[Holiday: New Years Day (month=1, day=1, observance=<function nearest_workday at 0x7f6afad571f0>),
 Holiday: Martin Luther King Jr. Day (month=1, day=1, offset=<DateOffset: weekday=MO( 3)>),
 Holiday: Presidents Day (month=2, day=1, offset=<DateOffset: weekday=MO( 3)>),
 Holiday: Memorial Day (month=5, day=31, offset=<DateOffset: weekday=MO(-1)>),
 Holiday: July 4th (month=7, day=4, observance=<function nearest_workday at 0x7f6afad571f0>),
 Holiday: Labor Day (month=9, day=1, offset=<DateOffset: weekday=MO( 1)>),
 Holiday: Veterans Day (month=11, day=11, observance=<function nearest_workday at 0x7f6afad571f0>),
 Holiday: Thanksgiving (month=11, day=1, offset=<DateOffset: weekday=TH( 4)>),
 Holiday: Christmas (month=12, day=25, observance=<function nearest_workday at 0x7f6afad571f0>)]

uj5u.com熱心網友回復：

[T]他的代碼位于一個函式中，該函式被重復呼叫（在回圈中）以生成多個獨立的輸出......我嘗試通過重新加載importlib.reload無濟于事。

如果你真的想import和pop在函式內部，reload該holiday模塊就像這樣：

from importlib import reload

def f():
    from pandas.tseries import holiday

    # reload `holiday` and pop Columbus Day
    holiday = reload(holiday)
    cal = holiday.USFederalHolidayCalendar()
    cal.rules.pop(6) # as HenryEcker noted, do not assign back to `cal`

    # just for demo, print the first 3 letters per remaining holiday
    print([rule.name[:3] for rule in cal.rules])

for _ in range(10):
    f()

只是為了表明沒有Columbus 日，列印每個剩余假期的前 3 個字母：

['New', 'Mar', 'Pre', 'Mem', 'Jul', 'Lab', 'Vet', 'Tha', 'Chr']
['New', 'Mar', 'Pre', 'Mem', 'Jul', 'Lab', 'Vet', 'Tha', 'Chr']
['New', 'Mar', 'Pre', 'Mem', 'Jul', 'Lab', 'Vet', 'Tha', 'Chr']
['New', 'Mar', 'Pre', 'Mem', 'Jul', 'Lab', 'Vet', 'Tha', 'Chr']
['New', 'Mar', 'Pre', 'Mem', 'Jul', 'Lab', 'Vet', 'Tha', 'Chr']
['New', 'Mar', 'Pre', 'Mem', 'Jul', 'Lab', 'Vet', 'Tha', 'Chr']
['New', 'Mar', 'Pre', 'Mem', 'Jul', 'Lab', 'Vet', 'Tha', 'Chr']
['New', 'Mar', 'Pre', 'Mem', 'Jul', 'Lab', 'Vet', 'Tha', 'Chr']
['New', 'Mar', 'Pre', 'Mem', 'Jul', 'Lab', 'Vet', 'Tha', 'Chr']
['New', 'Mar', 'Pre', 'Mem', 'Jul', 'Lab', 'Vet', 'Tha', 'Chr']

但是如果可能的話，直接傳入cal函式，這樣你只需要生成和修改cal一次：

# define the function to accept `cal` to avoid repeated importing/reloading
def f(cal):
    print([rule.name[:3] for rule in cal.rules])

# generate `cal` and pop once
from pandas.tseries.holiday import USFederalHolidayCalendar
cal = USFederalHolidayCalendar()
cal.rules.pop(6) # as HenryEcker noted, do not assign back to `cal`

for _ in range(10):
    f(cal)

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