bigframes.pandas.api.typing.DataFrameGroupBy.rank

DataFrameGroupBy.rank(method='average', ascending: bool = True, na_option: str = 'keep', pct: bool = False) → DataFrame

Provide the rank of values within each group.

Examples:

>>> import bigframes.pandas as bpd
>>> df = bpd.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

[10 rows x 2 columns]
>>> 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

[10 rows x 7 columns]

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.

• ascending (bool, 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.

• pct (bool, default False) – Compute percentage rank of data within each group

Returns:

DataFrame with ranking of values within each group