pyspark.pandas.groupby.GroupBy.shift#

GroupBy.shift(periods=1, fill_value=None)[source]#

Shift each group by periods observations.

Parameters
periodsinteger, default 1

number of periods to shift

fill_valueoptional
Returns
Series or DataFrame

Object shifted within each group.

Examples

>>> df = ps.DataFrame({
...     'a': [1, 1, 1, 2, 2, 2, 3, 3, 3],
...     'b': [1, 2, 2, 2, 3, 3, 3, 4, 4]}, columns=['a', 'b'])
>>> df
   a  b
0  1  1
1  1  2
2  1  2
3  2  2
4  2  3
5  2  3
6  3  3
7  3  4
8  3  4

>>> df.groupby('a').shift().sort_index()  
     b
0  NaN
1  1.0
2  2.0
3  NaN
4  2.0
5  3.0
6  NaN
7  3.0
8  4.0

>>> df.groupby('a').shift(periods=-1, fill_value=0).sort_index()  
   b
0  2
1  2
2  0
3  3
4  3
5  0
6  4
7  4
8  0