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Pandas 日期时间索引上限到一天中的特定时间

[英]Pandas datetime index ceil to specific hour in day

I have a datetime index which I would like to round up(ceil) to a specific hour in the day.我有一个日期时间索引,我想将其四舍五入(ceil)到一天中的特定时间。 I am already aware of pandas' offset aliases and how they work, but specifically I would like to tell it to round the datetime to a specific hour in the day(or a specific day in the month).我已经知道 pandas 的偏移别名及其工作方式,但具体来说,我想告诉它将日期时间四舍五入到一天中的特定时间(或一个月中的特定日期)。 For example I would like to have this kind of transformation:例如,我想进行这种转换:

print(results.index)
DatetimeIndex(['2018-12-14 05:00:00+01:00', '2018-12-14 06:00:00+01:00',
           '2018-12-14 07:00:00+01:00', '2018-12-14 08:00:00+01:00',
           '2018-12-14 09:00:00+01:00', '2018-12-14 10:00:00+01:00',
           '2018-12-14 11:00:00+01:00', '2018-12-14 12:00:00+01:00',
           '2018-12-14 13:00:00+01:00', '2018-12-14 14:00:00+01:00',

Turns into变成

DatetimeIndex(['2018-12-14 08:00:00+01:00', '2018-12-14 08:00:00+01:00',
           '2018-12-14 08:00:00+01:00', '2018-12-14 08:00:00+01:00',
           '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00',
           '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00',
           '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00',

As far as I'm aware, there does not exist such a parameter that we can pass to ceil() that would allow this, since we can only round to nearest hour, day, month(freq='H', 'D', 'M')... Is there an elegant solution to this or would I have to code my own for loop?据我所知,不存在我们可以传递给 ceil() 的参数,因为我们只能四舍五入到最近的小时、天、月(freq='H', 'D' , 'M')... 对此是否有优雅的解决方案,或者我是否必须编写自己的 for 循环代码?

One idea is use numpy.where and offsets.DateOffset - here hour without s means set values to 8 , day with s means add one day to original days:一个想法是使用numpy.whereoffsets.DateOffset - 这里没有s hour意味着将值设置为8 ,带s day意味着在原始日期基础上增加一天:

d = pd.DatetimeIndex(['2018-12-14 05:00:00+01:00', '2018-12-14 06:00:00+01:00',
                      '2018-12-14 07:00:00+01:00', '2018-12-14 08:00:00+01:00',
                      '2018-12-14 09:00:00+01:00', '2018-12-14 10:00:00+01:00',
                      '2018-12-14 11:00:00+01:00', '2018-12-14 12:00:00+01:00',
                      '2018-12-14 13:00:00+01:00', '2018-12-14 14:00:00+01:00'])
           
results = pd.DataFrame(index=d)

out = np.where(results.index.hour <= 8, 
               results.index + pd.offsets.DateOffset(hour=8), 
               results.index + pd.offsets.DateOffset(days=1, hour=8))

print (pd.DatetimeIndex(out))
DatetimeIndex(['2018-12-14 08:00:00+01:00', '2018-12-14 08:00:00+01:00',
               '2018-12-14 08:00:00+01:00', '2018-12-14 08:00:00+01:00',
               '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00',
               '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00',
               '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00'],
              dtype='datetime64[ns, pytz.FixedOffset(60)]', freq=None)

Another idea is use Timedelta s and add day only if condition is True :另一个想法是使用Timedelta s 并仅在条件为True时添加日期:

m = results.index.hour > 8
out = results.index + pd.offsets.DateOffset(hour=8)  + pd.Timedelta(days=1) * m
print (out)
DatetimeIndex(['2018-12-14 08:00:00+01:00', '2018-12-14 08:00:00+01:00',
               '2018-12-14 08:00:00+01:00', '2018-12-14 08:00:00+01:00',
               '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00',
               '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00',
               '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00'],
              dtype='datetime64[ns, pytz.FixedOffset(60)]', freq=None)

m = results.index.hour > 8
out = results.index.floor('d') + pd.Timedelta(hours=8)  + pd.Timedelta(days=1) * m
print (out)
DatetimeIndex(['2018-12-14 08:00:00+01:00', '2018-12-14 08:00:00+01:00',
               '2018-12-14 08:00:00+01:00', '2018-12-14 08:00:00+01:00',
               '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00',
               '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00',
               '2018-12-15 08:00:00+01:00', '2018-12-15 08:00:00+01:00'],
              dtype='datetime64[ns, pytz.FixedOffset(60)]', freq=None)

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