将numpy数组的第二列转换为虚数

>>> Z = np.array([[1, 2], [3, 4], [5, 6]])
>>> print(Z)
[[1 2]
 [3 4]
 [5 6]]

>>> Z[:, 1] = (Z[:, 1]) * 1j
ComplexWarning: Casting complex values to real discards the imaginary part
>>> print(Z)
[[1 0]
 [3 0]
 [5 0]]

[[1+2.j]
 [3+4.j]
 [5+6.j]]