为什么带有正参数的 relativedelta return 是过去的日期？

Question

我无法理解 dateutil.relativedelta 的行为。我知道如果我使用 relativedelta doc.

中指定的否定参数，relativedelta 可以 return 过去的日期

但是，当我提供正参数时，我希望它总是 return 将来的日期......这似乎是合法的吧？

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

所以根据你的初始日期，你实际上是早上 8 点，但是你通过使用 hour 参数将目标定为早上 6 点，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)

Answer 2

我认为它在文档中：

开始于，大约 weekday：

These instances may receive a parameter N, specifying the Nth weekday, which could be positive or negative (like MO(+1) or MO(-2). Not specifying it is the same as specifying +1.

所以通过 1，就像您通过了 (1, 1)

然后，继续文档，在 behavior of operations with relativedelta 的第 7 个点：

Notice that if the calculated date is already Monday, for example, using (0, 1) or (0, -1) won’t change the day.

所以 11 月 29 日已经是星期二了，而您要的是星期二。

所以什么都没有改变。

为什么带有正参数的 relativedelta return 是过去的日期？

Why does relativedelta with positive arguments return a date in the past?

python

python-dateutil

relativedelta