Python 将DateTimeindex转换为仅包含年、小时和日,而不包含时间信息
我有一个数据帧,其索引也包含Hour:second:。。。但是我只希望它包含日期,如年、月、日 索引是否可能仍然是DateTimeIndex,但只包含年、月、日 当前索引如下所示:Python 将DateTimeindex转换为仅包含年、小时和日,而不包含时间信息,python,pandas,Python,Pandas,我有一个数据帧,其索引也包含Hour:second:。。。但是我只希望它包含日期,如年、月、日 索引是否可能仍然是DateTimeIndex,但只包含年、月、日 当前索引如下所示: my_index = DatetimeIndex(['2017-08-25', '2017-08-24', '2017-08-23', '2017-08-22', '2017-08-21', '2017-08-20', '2017-08-19', '2017-08-18',
my_index = DatetimeIndex(['2017-08-25', '2017-08-24', '2017-08-23', '2017-08-22',
'2017-08-21', '2017-08-20', '2017-08-19', '2017-08-18',
'2017-08-17', '2017-08-16',
...
'2015-07-19', '2015-07-18', '2015-07-17', '2015-07-16',
'2015-07-15', '2015-07-14', '2015-07-13', '2015-07-12',
'2015-07-11', '2015-07-10'],
dtype='datetime64[ns]', length=778, freq=None)
我可以做到:
only_date_index = [el.date() for el in my_index]
但是如果我想在pandas中使用重采样功能,我会得到错误:
TypeError:仅对DatetimeIndex、TimedeltaIndex或PeriodIndex有效,但获得了“Index”的实例。您需要:
样本:
rng = pd.date_range('2017-04-03 15:00:45', periods=10, freq='24T')
df = pd.DataFrame({'a': range(10)}, index=rng)
print (df)
a
2017-04-03 15:00:45 0
2017-04-03 15:24:45 1
2017-04-03 15:48:45 2
2017-04-03 16:12:45 3
2017-04-03 16:36:45 4
2017-04-03 17:00:45 5
2017-04-03 17:24:45 6
2017-04-03 17:48:45 7
2017-04-03 18:12:45 8
2017-04-03 18:36:45 9
myIndex = df.index.floor('D')
print (myIndex)
DatetimeIndex(['2017-04-03', '2017-04-03', '2017-04-03', '2017-04-03',
'2017-04-03', '2017-04-03', '2017-04-03', '2017-04-03',
'2017-04-03', '2017-04-03'],
dtype='datetime64[ns]', freq=None)
感谢您提供另一个解决方案-使用:
计时:
ix = pd.date_range('1970-01-01', '2200-01-15', freq='1H')
print (len(ix))
2016481
In [68]: %timeit (ix.normalize())
10 loops, best of 3: 178 ms per loop
In [69]: %timeit (ix.floor('d'))
10 loops, best of 3: 38.4 ms per loop
#solution from Dror (https://stackoverflow.com/questions/45954497/in-pandas-group-by-date-from-datetimeindex)
In [70]: %timeit pd.to_datetime(ix.date)
1 loop, best of 3: 5.09 s per loop
尝试.normalize()
它将使时间变为午夜,因为我相信DateTimeIndex
需要时间。normalize()
也可以做到这一点,它是DateTimeIndex数组的嵌入式函数,但不是单个实例
myIndex = df.index.normalize()
print (myIndex)
DatetimeIndex(['2017-04-03', '2017-04-03', '2017-04-03', '2017-04-03',
'2017-04-03', '2017-04-03', '2017-04-03', '2017-04-03',
'2017-04-03', '2017-04-03'],
dtype='datetime64[ns]', freq=None)
ix = pd.date_range('1970-01-01', '2200-01-15', freq='1H')
print (len(ix))
2016481
In [68]: %timeit (ix.normalize())
10 loops, best of 3: 178 ms per loop
In [69]: %timeit (ix.floor('d'))
10 loops, best of 3: 38.4 ms per loop
#solution from Dror (https://stackoverflow.com/questions/45954497/in-pandas-group-by-date-from-datetimeindex)
In [70]: %timeit pd.to_datetime(ix.date)
1 loop, best of 3: 5.09 s per loop