pandas 에 rank 라는 메소드가 있습니다.

• https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.rank.html
• https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.rank.html

Python 3.8.5 (tags/v3.8.5:580fbb0, Jul 20 2020, 15:57:54) [MSC v.1924 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license()" for more information.
>>> import pandas as pd

>>> l = [4, 6, 6, 6, 7, 8, 8, 8, 9, 10, 10, 10, 10, 10, 11, 12, 12, 12, 12, 12, 20, 20]
>>> s = pd.Series(l)
>>> s
0      4
1      6
2      6
3      6
4      7
5      8
6      8
7      8
8      9
9     10
10    10
11    10
12    10
13    10
14    11
15    12
16    12
17    12
18    12
19    12
20    20
21    20
dtype: int64
>>> s.rank()
0      1.0
1      3.0
2      3.0
3      3.0
4      5.0
5      7.0
6      7.0
7      7.0
8      9.0
9     12.0
10    12.0
11    12.0
12    12.0
13    12.0
14    15.0
15    18.0
16    18.0
17    18.0
18    18.0
19    18.0
20    21.5
21    21.5
dtype: float64
>>> s.rank(method='max')
0      1.0
1      4.0
2      4.0
3      4.0
4      5.0
5      8.0
6      8.0
7      8.0
8      9.0
9     14.0
10    14.0
11    14.0
12    14.0
13    14.0
14    15.0
15    20.0
16    20.0
17    20.0
18    20.0
19    20.0
20    22.0
21    22.0
dtype: float64
>>>