使用日期工具。解析器来解释时区，但解析不会识别 tzinfos？

Question

我正在尝试从包含不同时区的列表中提取时间戳。 我正在使用 dateutil.parser。我相信我想为此使用 parse 函数，包括时区信息，但它似乎不想接受它们。谁能告诉我哪里出错了？

from dateutil.parser import parse
timezone_info = {
    "PDT": "UTC -7",
    "PST": "UTC -8",
    }
date_list = ['Oct 21, 2019 19:30 PDT',
             'Nov 4, 2019 18:30 PST']

for dates in date_list:
    print(parse(dates))
# This gives:
# 2019-10-21 19:30:00
# 2019-11-04 18:30:00

for date in date_list:
    print(parse(dates, tzinfos = timezone_info))

这是输出：

2019-10-21 19:30:00
2019-11-04 18:30:00
C:\Users\mbsta\Anaconda3\envs\untitled2\lib\site-packages\dateutil\parser\_parser.py:1218: UnknownTimezoneWarning: tzname PDT identified but not understood.  Pass `tzinfos` argument in order to correctly return a timezone-aware datetime.  In a future version, this will raise an exception.
  category=UnknownTimezoneWarning)
C:\Users\mbsta\Anaconda3\envs\untitled2\lib\site-packages\dateutil\parser\_parser.py:1218: UnknownTimezoneWarning: tzname PST identified but not understood.  Pass `tzinfos` argument in order to correctly return a timezone-aware datetime.  In a future version, this will raise an exception.
  category=UnknownTimezoneWarning)
Traceback (most recent call last):
  File "C:/Users/mbsta/PycharmProjects/untitled2/tester.py", line 16, in <module>
    print(parse(dates, tzinfos = timezone_info))
  File "C:\Users\mbsta\Anaconda3\envs\untitled2\lib\site-packages\dateutil\parser\_parser.py", line 1374, in parse
    return DEFAULTPARSER.parse(timestr, **kwargs)
  File "C:\Users\mbsta\Anaconda3\envs\untitled2\lib\site-packages\dateutil\parser\_parser.py", line 660, in parse
    ret = self._build_tzaware(ret, res, tzinfos)
  File "C:\Users\mbsta\Anaconda3\envs\untitled2\lib\site-packages\dateutil\parser\_parser.py", line 1185, in _build_tzaware
    tzinfo = self._build_tzinfo(tzinfos, res.tzname, res.tzoffset)
  File "C:\Users\mbsta\Anaconda3\envs\untitled2\lib\site-packages\dateutil\parser\_parser.py", line 1175, in _build_tzinfo
    tzinfo = tz.tzstr(tzdata)
  File "C:\Users\mbsta\Anaconda3\envs\untitled2\lib\site-packages\dateutil\tz\_factories.py", line 69, in __call__
    cls.instance(s, posix_offset))
  File "C:\Users\mbsta\Anaconda3\envs\untitled2\lib\site-packages\dateutil\tz\_factories.py", line 22, in instance
    return type.__call__(cls, *args, **kwargs)
  File "C:\Users\mbsta\Anaconda3\envs\untitled2\lib\site-packages\dateutil\tz\tz.py", line 1087, in __init__
    raise ValueError("unknown string format")
ValueError: unknown string format

Process finished with exit code 1

Answer 1

我认为这里的问题是您指定的偏移量不是tzstr 的有效格式，它需要看起来像TZ variable 的东西。如果将字符串分别更改为"PST+8" 和"PDT+7"，它将按预期工作。

也就是说，我认为您最好使用tzfile，这是tzinfos 的主要用途之一：

from dateutil import parser
from dateutil import tz
PACIFIC = tz.gettz("America/Los_Angeles")
timezone_info = {"PST": PACIFIC, "PDT": PACIFIC}

date_list = ["Oct 21, 2019 19:30 PDT",
             "Nov 4, 2019 18:30 PST"]

for dtstr in date_list:
    print(parser.parse(dtstr, tzinfos=timezone_info))

打印出来：

2019-10-21 19:30:00-07:00
2019-11-04 18:30:00-08:00

而且由于它附加了一个完整的时区偏移量，您可以对结果进行算术运算而不用担心（因为它是一个完整的时区，而不是一个固定的偏移量）。