fft.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.
Parameters:xarray_likeInput array.
axesint or shape tuple, optionalAxes over which to shift. Default is None, which shifts all axes.
Returns:yndarrayThe shifted array.
Examples
>>> importnumpyasnp>>> freqs=np.fft.fftfreq(10,0.1)>>> freqsarray([ 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)>>> freqsarray([[ 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.]])