>>> import numpy >>> numpy.eye(3) array([[ 1., 0., 0.],     [ 0., 1., 0.],     [ 0., 0., 1.]]) >>> numpy.zeros(3) array([ 0., 0., 0.]) >>> numpy.ones(3) array([ 1., 1., 1.]) >>> x1 = numpy.array((1, 2, 3)) >>> x1 array([1, 2, 3]) >>> x2 = numpy.array([4, 5, 6]) >>> x2 array([4, 5, 6]) >>> x3 = numpy.array((x1, x2)) >>> x3 array([[1, 2, 3],     [4, 5, 6]]) >>> x4 = x3.reshape(2, 3) >>> x4 array([[1, 2, 3],     [4, 5, 6]]) >>> x4 = x3.reshape(3, 2) >>> x4 array([[1, 2],     [3, 4],     [5, 6]]) >>> x5 = numpy.row_stack(x1, x2) Traceback (most recent call last):  File "<stdin>", line 1, in <module> TypeError: vstack() takes exactly 1 argument (2 given) >>> x5 = numpy.row_stack((x1, x2)) >>> x5 array([[1, 2, 3],     [4, 5, 6]]) >>> x6 = numpy.row_stack([x1, x2]) >>> x6 array([[1, 2, 3],     [4, 5, 6]]) >>> x7 = numpy.row_stack((x6, x2)) >>> x7 array([[1, 2, 3],     [4, 5, 6],     [4, 5, 6]]) >>> x7[0] array([1, 2, 3]) >>> x7[1] array([4, 5, 6]) >>> x7[2] array([4, 5, 6]) >>> x8 = numpy.column_stack([x1, x2, x1, x2]) >>> x8 array([[1, 4, 1, 4],     [2, 5, 2, 5],     [3, 6, 3, 6]]) >>> x8[0] array([1, 4, 1, 4]) >>> x8[1] array([2, 5, 2, 5]) >>> x8[2] array([3, 6, 3, 6]) >>> x8[3] Traceback (most recent call last):  File "<stdin>", line 1, in <module> IndexError: index 3 is out of bounds for axis 0 with size 3 >>> x8[0][3] 4 >>> 

print np.ones((1,4))*2