関連ワード:  how to empty a dataframe in python    how to delete a dataframe in python    how to clear a dataframe in python    how to clean a dataframe in python    how to empty a dataframe in pandas    how to create a empty dataframe in python    how to define a empty dataframe in python    how to declare a empty dataframe in python    how to make a empty dataframe in python    how to delete a dataframe column in python