`numpy.fft:fftshift`

Signature

def fftshift(x, axes = None)

Shift the zero-frequency component to the center of the spectrum.

This function swaps half-spaces for all axes listed (defaults to all). Note that y[0] is the Nyquist component only if len(x) is even.

x : array_like: Input array.
axes : int or shape tuple, optional: Axes over which to shift. Default is None, which shifts all axes.

import numpy as np
freqs = np.fft.fftfreq(10, 0.1)
freqs
np.fft.fftshift(freqs)

✓

array([-5., -4., -3., -2., -1.,  0.,  1.,  2.,  3.,  4.])

Shift the zero-frequency component only along the second axis:

freqs = np.fft.fftfreq(9, d=1./9).reshape(3, 3)
freqs
np.fft.fftshift(freqs, axes=(1,))

✓

array([[ 2.,  0.,  1.],
       [-4.,  3.,  4.],
       [-1., -3., -2.]])