test_reshape.py 文件源码

def test_value_vars(self):
        result3 = melt(self.df, id_vars=['id1', 'id2'], value_vars='A')
        self.assertEqual(len(result3), 10)

        result4 = melt(self.df, id_vars=['id1', 'id2'], value_vars=['A', 'B'])
        expected4 = DataFrame({'id1': self.df['id1'].tolist() * 2,
                               'id2': self.df['id2'].tolist() * 2,
                               'variable': ['A'] * 10 + ['B'] * 10,
                               'value': (self.df['A'].tolist() +
                                         self.df['B'].tolist())},
                              columns=['id1', 'id2', 'variable', 'value'])
        tm.assert_frame_equal(result4, expected4)