関連ワード:  how to create empty df in python    how to create empty dataframe in python    how to create empty dataframe in python with column names    how to initialize empty df in python    how to initialize empty dataframe in python    how to declare empty dataframe in python    how to create an empty dataframe in python pandas    how to create empty column in dataframe python    how to create new empty column in dataframe python    how to create an empty dataframe from another dataframe in python