mars.tensor.fft.
fftshift
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.
y[0]
len(x)
x (array_like) – Input tensor.
axes (int or shape tuple, optional) – Axes over which to shift. Default is None, which shifts all axes.
y – The shifted tensor.
Tensor
See also
ifftshift
The inverse of fftshift.
Examples
>>> import mars.tensor as mt
>>> freqs = mt.fft.fftfreq(10, 0.1) >>> freqs.execute() array([ 0., 1., 2., 3., 4., -5., -4., -3., -2., -1.]) >>> mt.fft.fftshift(freqs).execute() array([-5., -4., -3., -2., -1., 0., 1., 2., 3., 4.])
Shift the zero-frequency component only along the second axis:
>>> freqs = mt.fft.fftfreq(9, d=1./9).reshape(3, 3) >>> freqs.execute() array([[ 0., 1., 2.], [ 3., 4., -4.], [-3., -2., -1.]]) >>> mt.fft.fftshift(freqs, axes=(1,)).execute() array([[ 2., 0., 1.], [-4., 3., 4.], [-1., -3., -2.]])