In [18]: aOut[18]: x1 x20 0 51 1 62 2 73 3 84 4 9In [19]: a['x2'] = a.x2.shift(1)In [20]: aOut[20]: x1 x20 0 NaN1 1 52 2 63 3 74 4 8

In [18]: aOut[18]: x1 x20 0 51 1 62 2 73 3 84 4 9In [19]: a['x2'] = a.x2.shift(1)In [20]: aOut[20]: x1 x20 0 NaN1 1 52 2 63 3 74 4 8