numpy.fft.fftshift — NumPy v2.2 Manual (original) (raw)

fft.fftshift(x, axes=None)[source]#

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.

Parameters:

xarray_like

Input array.

axesint or shape tuple, optional

Axes over which to shift. Default is None, which shifts all axes.

Returns:

yndarray

The shifted array.

Examples

import numpy as np freqs = np.fft.fftfreq(10, 0.1) freqs array([ 0., 1., 2., ..., -3., -2., -1.]) 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 array([[ 0., 1., 2.], [ 3., 4., -4.], [-3., -2., -1.]]) np.fft.fftshift(freqs, axes=(1,)) array([[ 2., 0., 1.], [-4., 3., 4.], [-1., -3., -2.]])