periods： Express shift Range of movement , A positive number means to move down , Negative numbers move up , The default value is 1, After the move, there is no value, and the index is missing
freq： according to freq The parameter value is used as the interval moving time index , The data value does not change , About freq You can obtain values for reference date_range Create date range freq Parameter value table and creation example _ I am a little monster blog -CSDN Blog
>>> import pandas as pd
>>> date_index=pd.date_range('2022-01-01',periods=6)
>>> time=pd.Series(range(6),index=date_index)
>>> print(time)
2022-01-01 0
2022-01-02 1
2022-01-03 2
2022-01-04 3
2022-01-05 4
2022-01-06 5
Freq: D, dtype: int64
>>> time.shift(periods=2)# Move down the 2 Time
2022-01-01 NaN
2022-01-02 NaN
2022-01-03 0.0
2022-01-04 1.0
2022-01-05 2.0
2022-01-06 3.0
Freq: D, dtype: float64
>>> time.shift(periods=-2)# Move up 2 Time
2022-01-01 2.0
2022-01-02 3.0
2022-01-03 4.0
2022-01-04 5.0
2022-01-05 NaN
2022-01-06 NaN
Freq: D, dtype: float64
>>> time.shift(periods=-2,freq='2D')# Every two days , Move up twice , So the time index shifted for four days
2021-12-28 0
2021-12-29 1
2021-12-30 2
2021-12-31 3
2022-01-01 4
2022-01-02 5
Freq: D, dtype: int64
>>> time.shift(periods=-1,freq='2D')
2021-12-30 0
2021-12-31 1
2022-01-01 2
2022-01-02 3
2022-01-03 4
2022-01-04 5
Freq: D, dtype: int64
