関連ワード:  how to join two columns in python    how to concatenate two columns in python    how to combine two columns in python    how to merge two columns in python dataframe    how to append two columns in python    how to merge two columns in python pandas    how to concatenate two columns in python dataframe    how to combine two columns in python dataframe    how to concatenate two columns in python pandas    how to concatenate 2 columns in python