# pandas.core.groupby.GroupBy.ngroup

`GroupBy.``ngroup`(ascending=True)

  Number each group from 0 to the number of groups - 1.

  This is the enumerative complement of cumcount. Note that the numbers given to the groups match the order in which the groups would be seen when iterating over the groupby object, not the order they are first observed.

  New in version 0.20.2.

  Parameters:

  ascending : bool, default True

  > If False, number in reverse, from number of group - 1 to 0.

  See also

  `pandas.Series.groupby`, `pandas.DataFrame.groupby`, `pandas.Panel.groupby`

  Examples

      >>> df = pd.DataFrame({"A": list("aaabba")})
      >>> df
         A
      0  a
      1  a
      2  a
      3  b
      4  b
      5  a
      >>> df.groupby('A').ngroup()
      0    0
      1    0
      2    0
      3    1
      4    1
      5    0
      dtype: int64
      >>> df.groupby('A').ngroup(ascending=False)
      0    1
      1    1
      2    1
      3    0
      4    0
      5    1
      dtype: int64
      >>> df.groupby(["A", [1,1,2,3,2,1]]).ngroup()
      0    0
      1    0
      2    1
      3    3
      4    2
      5    0
      dtype: int64

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