pandas - set attribute when attribute changes in python -

i have class has attribute pandas dataframe. define attribute in same class changes when dataframe altered. thought setter might correct approach haven't been able work. here toy example:

import pandas pd  class foo(object):     def __init__(self, df=none):         self._df = df         self.altered = false # bool, set true if self._df changes     @property     def df(self):         return self._df     @df.setter     def df(self, df):         self.altered = true # since _df might change here set self.altered true         self._df = df  df_test = pd.dataframe([[1,2,3]], columns=['a','b','c'])  cl = foo(df_test) cl.df.loc[0, 'a'] = 3 # change default value in dataframe print(cl.df) print(cl.altered) 

which prints altered dataframe cl.altered still set false.

any suggestions?

i don't know pandas. setter isn't called because line was:

cl.df.loc[0, 'a'] = 3 

it have been called if line was:

cl.df = 3 

one thing store copy of original df when instance initialized , like:

@property def altered(self):     return self._orig_df == self._current_df