How can I replace the column values in a pandas data frame with a sequence of consecutive numbers?

Question

I have removed some rows from my dataframe and therefore need to reset the rank column. I have sorted the rank column in descending order and now need to redo the numbering. Any suggestions?

Current df:

Country   Rank  
GB        1
SGP       3
CHE       4
USA       8
IRL       9

Desired df:

Country   Rank  
GB        1
SGP       2
CHE       3
USA       4
IRL       5

Answer 1

You can use below code:
df['Rank'] = range(1, 1+len(df))

Answer 2

import pandas as pd 
data = {'Country': ['GB', 'SGP', 'CHE', 'USA', 'IRL'], 'Rank': [1, 3, 4, 8, 9],} 
df = pd.DataFrame(data)
'''You can generate a list of intger range, from 1 to the length of you dataframe + 1, then overwrite your rank column with it'''
df['Rank'] = range(1,len(df)+1) 
print(df)