Pandas 按列排名

Question

New to Python here, I'm looking to create a column in my dataframe that ranks a column based off its value. Specifically in this situation, I have a balance field, and I want to rank the highest balance as 1, the second highest balance as 2, so on so forth. However when I try to use the rank function, min or dense or any other option, it does not rank according to the balance... my attempt is below:

import pandas as pd

# Create a test df
df = pd.DataFrame({'Name': ['Bob','Carl','Doug','Edith','Ford','George']
                  , 'Bank Amt': ['17','123','144','2','63','25']
                  , 'Loan Amt': ['147','1523','1144','542','5463','2135']
                  })


df['Bank Amt Rank'] = df['Bank Amt'].rank(method='min', ascending=True)

df

Output:

Any help would be appreciated.

Answer 1

your data is string type, you need to convert to numerical type:

df['Bank Amt'].astype(float).rank()

Output:

0    2.0
1    5.0
2    6.0
3    1.0
4    4.0
5    3.0
Name: Bank Amt, dtype: float64