table from wikipedia

[snippsat]

#1 How can I change (in 'Rank'):
*index 221: 0 to the number 191?
*indexes 223, 224, 225: 0 to the number 192?

Try using df.ffill().

import pandas as pd
import numpy as np

df = pd.DataFrame({'A': [1, 2, np.nan, 4, np.nan, 6],
           'B': [200, np.nan, np.nan, 201, 202, 203]})

df

	A	B
0	1.0	200.0
1	2.0	NaN
2	NaN	NaN
3	4.0	201.0
4	NaN	202.0
5	6.0	203.0

df.ffill()

A	B
0	1.0	200.0
1	2.0	200.0
2	2.0	200.0
3	4.0	201.0
4	4.0	202.0
5	6.0	203.0