Python: error in writing class -

i want write func , add class. use

import pandas pd import tldextract  domain = [] df = pd.dataframe() df['urls'] = ['ru.vk.com', 'eng.facebook.com', 'ru.ya.ru'] urls = df.urls.values.tolist() class csv:     def get_domain(self, list_url, list, df):         self.list_url = list_url         self.list = list         self.df = df         i, url in enumerate(list_url):             get_domain = tldextract.extract(url)             subdomain = get_domain[0] + '.' + get_domain[1] + '.' + get_domain[2]             if subdomain.startswith('.'):                 subdomain = subdomain[1:]             elif subdomain.endswith('.'):                 subdomain = subdomain[:-1]             elif subdomain.startswith('www.'):                 subdomain = subdomain[4:]             list.append(subdomain)         df['subdomain'] = list  df = csv() df.get_domain(urls, domain, df) 

i try domain urls, error

attributeerror: csv instance has no attribute '__setitem__' 

what should change?

you named variable use create csv instance df, same data frame item, making df refer csv object , not panda dataframe. then, when try call get domain, df refers class, has no way string indices, failing.

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in short - change variable name in last 2 rows, like

csv_df = csv() csv_df.get_domain(urls, domain, df) 

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by way, it's not mistake, i'm pretty sure last row on get_domain supposed be

self.df['subdomain'] = self.list 

(same goes variables across function, since desire change class property , not given variable).

and shouldn't name variable list or other reserved keyword. might cause issues.