python else statement causes a continuous loop

Question

Not understanding why my Python else statement is causing an infinite loop?

m = 0
while m < len(dataframe):
    if dataframe['firstname'].iloc[m] == 'Donald':
       dataframe.loc[m, 'lastname'] = 'Trump'
    elif dataframe['firstname'].iloc[m] == 'Joe':
       dataframe.loc[m, 'lastname'] = 'Biden'
    elif dataframe['firstname'].iloc[m] == 'Barrack':
       dataframe.loc[m, 'lastname'] = 'Obama'
    else:
       dataframe.loc[m, 'lastname'] = 'last name does not matter'
   
    m+=1

Answer 1

I have tested your code locally. I don't have infinite loop. Here is the code I have:

import pandas as pd
dataframe = pd.DataFrame({"firstname": ["Donald", "Joe", "Barrack", "Kamala"], "lastname": ["", "", "" ,""]})
m = 0
while m < len(dataframe):
    if dataframe['firstname'].iloc[m] == 'Donald':
       dataframe.loc[m, 'lastname'] = 'Trump'
    elif dataframe['firstname'].iloc[m] == 'Joe':
       dataframe.loc[m, 'lastname'] = 'Biden'
    elif dataframe['firstname'].iloc[m] == 'Barrack':
       dataframe.loc[m, 'lastname'] = 'Obama'
    else:
       dataframe.loc[m, 'lastname'] = 'last name does not matter'
   
    m+=1
print(dataframe)

I would recommend using for loops so you can't get infinite loops though:

import pandas as pd
dataframe = pd.DataFrame({"firstname": ["Donald", "Joe", "Barrack", "Kamala"], "lastname": ["", "", "" ,""]})
for i in range(len(dataframe)):
    if dataframe['firstname'].iloc[i] == 'Donald':
       dataframe.loc[i, 'lastname'] = 'Trump'
    elif dataframe['firstname'].iloc[i] == 'Joe':
       dataframe.loc[i, 'lastname'] = 'Biden'
    elif dataframe['firstname'].iloc[i] == 'Barrack':
       dataframe.loc[i, 'lastname'] = 'Obama'
    else:
       dataframe.loc[i, 'lastname'] = 'last name does not matter'
   
print(dataframe)

Hope this helps!