pandas.core.groupby.SeriesGroupBy.rank#

SeriesGroupBy.rank(method='average', ascending=True, na_option='keep', pct=False)[source]#

Provide the rank of values within each group.

Parameters:
method{‘average’, ‘min’, ‘max’, ‘first’, ‘dense’}, default ‘average’

  • average: average rank of group.

  • min: lowest rank in group.

  • max: highest rank in group.

  • first: ranks assigned in order they appear in the array.

  • dense: like ‘min’, but rank always increases by 1 between groups.

ascendingbool, default True

False for ranks by high (1) to low (N).

na_option{‘keep’, ‘top’, ‘bottom’}, default ‘keep’

  • keep: leave NA values where they are.

  • top: smallest rank if ascending.

  • bottom: smallest rank if descending.

pctbool, default False

Compute percentage rank of data within each group.

Returns:
DataFrame

The ranking of values within each group.

See also

Series.groupby

Apply a function groupby to a Series.

DataFrame.groupby

Apply a function groupby to each row or column of a DataFrame.

Examples

>>> df = pd.DataFrame(
...     {
...         "group": ["a", "a", "a", "a", "a", "b", "b", "b", "b", "b"],
...         "value": [2, 4, 2, 3, 5, 1, 2, 4, 1, 5],
...     }
... )
>>> df
  group  value
0     a      2
1     a      4
2     a      2
3     a      3
4     a      5
5     b      1
6     b      2
7     b      4
8     b      1
9     b      5
>>> for method in ["average", "min", "max", "dense", "first"]:
...     df[f"{method}_rank"] = df.groupby("group")["value"].rank(method)
>>> df
  group  value  average_rank  min_rank  max_rank  dense_rank  first_rank
0     a      2           1.5       1.0       2.0         1.0         1.0
1     a      4           4.0       4.0       4.0         3.0         4.0
2     a      2           1.5       1.0       2.0         1.0         2.0
3     a      3           3.0       3.0       3.0         2.0         3.0
4     a      5           5.0       5.0       5.0         4.0         5.0
5     b      1           1.5       1.0       2.0         1.0         1.0
6     b      2           3.0       3.0       3.0         2.0         3.0
7     b      4           4.0       4.0       4.0         3.0         4.0
8     b      1           1.5       1.0       2.0         1.0         2.0
9     b      5           5.0       5.0       5.0         4.0         5.0