python - 为什么带有正参数的 relativedelta 返回过去的日期？

Question

我很难理解 dateutil.relativedelta 的行为。我知道如果我使用 relativedelta doc 中指定的否定参数，relativedelta 可能会返回过去的日期.

但是，当我提供正参数时，我希望它总是返回一个 future 的日期……这似乎是对的吧？

我的用例如下:我们是星期二，现在是 8:35。我想在 6:00 获取最近的星期一和星期二的日期。

这是我所做的。第一个结果对我来说似乎是正确的，而第二个结果是错误的。

>>> import datetime
>>> now = datetime.datetime.now()
>>> now
datetime.datetime(2016, 11, 29, 8, 35, 23, 786349)

>>> from dateutil import relativedelta
>>> now.weekday()
1

>>> now + relativedelta.relativedelta(weekday=0, hour=6, minute=0) # should give a time in the future
datetime.datetime(2016, 12, 5, 6, 0, 23, 786349)  # here this is correct, in the future

>>> now + relativedelta.relativedelta(weekday=1, hour=6, minute=0) # should give a time in the future
datetime.datetime(2016, 11, 29, 6, 0, 23, 786349)  # but this is in the past / I would expect result (2016, 12, 6, 6, 0, 23, 786349)

那么，我是不是做错了什么？

Answer 1

因此，根据您的初始日期，您实际上是早上 8 点，但您使用 hour 将目标定为早上 6 点。参数，如果你想增加一小时，你应该使用 hours和 minutes分别

>>> now
datetime.datetime(2016, 11, 29, 3, 5, 41, 763818)

>>> now.weekday()
1

>>> now + relativedelta.relativedelta(weekday=1, hour=1)
datetime.datetime(2016, 11, 29, 1, 5, 41, 763818) # Notice how it's in the past

>>> now + relativedelta.relativedelta(weekday=1, hours=1)
datetime.datetime(2016, 11, 29, 4, 5, 41, 763818) # Notice how it's one hour in the future

>>> n + relativedelta.relativedelta(weekday=1, hour=6, minute=0, weeks=1)
datetime.datetime(2016, 12, 6, 6, 0, 41, 763818)