How to change the column values in pandas based on some condition

I want to change the column values in a dataframe to another name when it matches some certain conditions.

I tried apply method on the dataframe but it didnt work.

This is the dataset i have and i want the country column names should be changed on some condition. For example “Republic of Korea” should be change to ‘South Korea’ and I have similar names that needs to be changed in this column. I tried apply method and i’m not getting any results. Any suggestions would help me. Thank you in advance. **

df.head()

       Country Energy_Supply Energy_Supply_per_Capita   
0      Afghanistan      3.210000e       10.0    
1      Albania          1.020000e       35.0    
2      Algeria          1.959000e+09    51.0    
3      American Samoa   NaN             NaN 

Answer

You can use replace() for your column of interest. Create a dictionary repl_dict = {"Republic of China": "China", "Republic of Moldova": "Moldova", "Republic of France": "France","Great Britain": "England"} and then pass is to replace function, for more details and parameters check pandas.DataFrame.replace

This method does replace all at once by creating the dictionary with all the names of interest, ultimately will standardize your dataframe column based on this dictionary and no need to run individually for each Country.

import pandas as pd
my_dict = { 'Country' : ["Republic of China", "China", "England", "Republic of Moldova", "Republic of France","Great Britain", "England"],
                   'age' : [20,27, 35, 55, 18, 21, 35],
                   'designation': ["VP", "CEO", "CFO", "VP", "VP", "CEO", "MD"]}

dfnew = pd.DataFrame(my_dict)
print(dfnew)

Country  age designation
0    Republic of China   20          VP
1                China   27         CEO
2              England   35         CFO
3  Republic of Moldova   55          VP
4   Republic of France   18          VP
5        Great Britain   21         CEO
6              England   35          MD

repl_dict = {"Republic of China": "China", "Republic of Moldova": "Moldova", "Republic of France": "France","Great Britain": "England"}
dfnew['Country'] = dfnew['Country'].replace(repl_dict, regex=True)
print()
print('Final dataframe', dfnew)

Final dataframe    
Country  age designation
0    China   20          VP
1    China   27         CEO
2  England   35         CFO
3  Moldova   55          VP
4   France   18          VP
5  England   21         CEO
6  England   35          MD