関連ワード:  how to define np array in python    how to initialize np array in python    how to declare numpy array in python    how to initialize numpy array in python    how to define 2d numpy array in python    how to define an empty numpy array in python    how to initialize empty numpy array in python    how to initialize an empty np array in python    how to initialize a 2d numpy array in python    how to convert dictionary to numpy array in python