pandas.core.groupby.GroupBy.cumcount¶
- GroupBy.cumcount(ascending=True)¶
Number each item in each group from 0 to the length of that group - 1.
Essentially this is equivalent to
>>> self.apply(lambda x: Series(np.arange(len(x)), x.index))
Parameters: ascending : bool, default True
If False, number in reverse, from length of group - 1 to 0.
Examples
>>> df = pd.DataFrame([['a'], ['a'], ['a'], ['b'], ['b'], ['a']], ... columns=['A']) >>> df A 0 a 1 a 2 a 3 b 4 b 5 a >>> df.groupby('A').cumcount() 0 0 1 1 2 2 3 0 4 1 5 3 dtype: int64 >>> df.groupby('A').cumcount(ascending=False) 0 3 1 2 2 1 3 1 4 0 5 0 dtype: int64