python - 如何使用 Pandas Timestamp 折叠参数？

Question

在处理时区转换和 dst 影响时，我很难弄清楚 Timestamp 构造函数的 fold 参数的 Pandas 实现。 documentation提及:

Due to daylight saving time, one wall clock time can occur twice when shifting from summer to winter time; fold describes whether the datetime-like corresponds to the first (0) or the second time (1) the wall clock hits the ambiguous time.

到目前为止并不奇怪，但是当我运行以下代码时:

import pandas as pd
from datetime import datetime

pre_fold = pd.Timestamp(datetime(2022,10,30,1,30,0), tz="CET")
in_fold_fold0 = pd.Timestamp(datetime(2022,10,30,2,30,0), tz="CET")
in_fold_fold1 = pd.Timestamp(datetime(2022,10,30,2,30,0), tz="CET", fold=1)
post_fold = pd.Timestamp(datetime(2022,10,30,3,30,0), tz="CET")

print(f"fold0: {in_fold_fold0.fold}")
print(f"fold1: {in_fold_fold1.fold}")

print(f"Pre CET fold:       {pre_fold}  ->  UTC {pre_fold.tz_convert(tz='UTC')}")
print(f"In CET fold, fold0: {in_fold_fold0}  ->  UTC {in_fold_fold0.tz_convert(tz='UTC')}")
print(f"In CET fold, fold1: {in_fold_fold1}  ->  UTC {in_fold_fold1.tz_convert(tz='UTC')}")
print(f"Post CET fold:      {post_fold}  ->  UTC {post_fold.tz_convert(tz='UTC')}")

输出不符合预期:

fold0: 0
fold1: 1
Pre CET fold:       2022-10-30 01:30:00+02:00  ->  UTC 2022-10-29 23:30:00+00:00
In CET fold, fold0: 2022-10-30 02:30:00+01:00  ->  UTC 2022-10-30 01:30:00+00:00
In CET fold, fold1: 2022-10-30 02:30:00+01:00  ->  UTC 2022-10-30 01:30:00+00:00
Post CET fold:      2022-10-30 03:30:00+01:00  ->  UTC 2022-10-30 02:30:00+00:00

第 4 行应该是:

In CET fold, fold0: 2022-10-30 02:30:00+02:00  ->  UTC 2022-10-30 00:30:00+00:00

我在这里错过了什么？

PS:使用 python 的 datetime 对象会产生预期的输出:

from datetime import datetime
from dateutil import tz

dt_pre_fold = datetime(2022,10,30,1,30,0, tzinfo=tz.gettz("CET"))
dt_in_fold_fold0 = datetime(2022,10,30,2,30,0, tzinfo=tz.gettz("CET"))
dt_in_fold_fold1 = datetime(2022,10,30,2,30,0, tzinfo=tz.gettz("CET"), fold=1)
dt_post_fold = datetime(2022,10,30,3,30,0, tzinfo=tz.gettz("CET"))

print(f"Pre CET fold:       {dt_pre_fold}  ->  UTC {dt_pre_fold.astimezone(tz.gettz('UTC'))}")
print(f"In CET fold, fold0: {dt_in_fold_fold0}  ->  UTC {dt_in_fold_fold0.astimezone(tz.gettz('UTC'))}")
print(f"In CET fold, fold1: {dt_in_fold_fold1}  ->  UTC {dt_in_fold_fold1.astimezone(tz.gettz('UTC'))}")
print(f"Post CET fold:      {dt_post_fold}  ->  UTC {dt_post_fold.astimezone(tz.gettz('UTC'))}")

输出:

Pre CET fold:       2022-10-30 01:30:00+02:00  ->  UTC 2022-10-29 23:30:00+00:00
In CET fold, fold0: 2022-10-30 02:30:00+02:00  ->  UTC 2022-10-30 00:30:00+00:00
In CET fold, fold1: 2022-10-30 02:30:00+01:00  ->  UTC 2022-10-30 01:30:00+00:00
Post CET fold:      2022-10-30 03:30:00+01:00  ->  UTC 2022-10-30 02:30:00+00:00

Answer 1

似乎没有正确指定时区信息:

# using your code
x = pd.Timestamp(datetime(2022,10,30,2,30,0), fold = 0, tz="CET")
x.tz_convert('UTC')
# Timestamp('2022-10-30 01:30:00+0000', tz='UTC')

但是如果你使用 from dateutil import tz

x = pd.Timestamp(datetime(2022,10,30,2,30,0), fold = 0, tz=tz.gettz("CET"))
x.tz_convert('UTC')
# Timestamp('2022-10-30 00:30:00+0000', tz='UTC')

它返回正确的值