[ns]', freq=None)
>>> pd.date_range('2018-07-01', periods=3, freq='D')
DatetimeIndex(['2018-07-01',...'2018-07-02', '2018-07-03'], dtype='datetime64[ns]', freq='D')
to_datetime函数将列表中的元素转换为DatetimeIndex对象...-01-03'], dtype='datetime64[ns]', freq='D')
# 按一周,即7天
>>> pd.date_range('2018-01-01', periods=3, freq...='W')
DatetimeIndex(['2018-01-07', '2018-01-14', '2018-01-21'], dtype='datetime64[ns]', freq='W-SUN')...-01-01 01:00:00',
'2018-01-01 02:00:00'],
dtype='datetime64[ns]', freq='