Source code for xorbits._mars.tensor.fft.ifftshift
# Copyright 2022-2023 XProbe Inc.
# derived from copyright 1999-2021 Alibaba Group Holding Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
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import numpy as np
from ... import opcodes as OperandDef
from ..datasource import tensor as astensor
from .core import TensorFFTShiftBase, TensorFFTShiftMixin
class TensorIFFTShift(TensorFFTShiftBase, TensorFFTShiftMixin):
_op_type_ = OperandDef.IFFTSHIFT
def __init__(self, axes=None, **kw):
super().__init__(_axes=axes, **kw)
@classmethod
def _is_inverse(cls):
return True
def _set_inputs(self, inputs):
super()._set_inputs(inputs)
self._input = self._inputs[0]
def __call__(self, x):
return self.new_tensor([x], x.shape)
[docs]def ifftshift(x, axes=None):
"""
The inverse of `fftshift`. Although identical for even-length `x`, the
functions differ by one sample for odd-length `x`.
Parameters
----------
x : array_like
Input tensor.
axes : int or shape tuple, optional
Axes over which to calculate. Defaults to None, which shifts all axes.
Returns
-------
y : Tensor
The shifted tensor.
See Also
--------
fftshift : Shift zero-frequency component to the center of the spectrum.
Examples
--------
>>> import mars.tensor as mt
>>> 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.ifftshift(mt.fft.fftshift(freqs)).execute()
array([[ 0., 1., 2.],
[ 3., 4., -4.],
[-3., -2., -1.]])
"""
x = astensor(x)
dtype = np.fft.ifftshift(np.empty((1,) * max(1, x.ndim), dtype=x.dtype)).dtype
axes = TensorIFFTShift._process_axes(x, axes)
op = TensorIFFTShift(axes=axes, dtype=dtype)
return op(x)