AttributeError: 'int' object has no attribute 'split' even when dtype of object is a string

I have a list named 'state_lists' and I have a dataframe with column named 'ADDRESS'. I want to create a new column in my dataframe by

1. iterating through the ADDRESS column
2. if a state from the 'state_lists' is found in the ADDRESS column, the state is extrated into another column named STATE

I used this code below, before and and it worked but now it shows the error above

df["STATE"] = df["ADDRESS"].map(lambda x: state if ( state:=x.split()[-1]) in state_lists else np.nan)

What would be the problem now? I have checked the data type for the Address column and it is an object. This code has worked before dont know what is happening now?

I make sure I replaced all the null values with an object still the same error message pops up

IIUC, you can use :

import re

pat = fr'\b({"|".join(map(re.escape, state_lists))})\b'

df["STATE"] = df["ADDRESS"].str.extract(pat, expand=False)

Seems you have int in your field ADDRESS. You can add a conditional statement to check if the value in ADDRESS is an instance of string before applying split() function. You can implement it as:

import numpy as np

def extract_state(address):
    if isinstance(address, str):
        state = address.split()[-1]
        return state if state in state_lists else np.nan
    else:
        return np.nan

df["STATE"] = df["ADDRESS"].map(extract_state)