from scipy.fftpack import fft, ifft
import numpy as np

x = np.array([1, 2, 4, 5])

x

array([1, 2, 4, 5])

y = fft(x)

y

array([12.+0.j, -3.+3.j, -2.+0.j, -3.-3.j])

y_inv = ifft(y)

y_inv

array([1.+0.j, 2.+0.j, 4.+0.j, 5.+0.j])