168 lines
6.0 KiB
Python
168 lines
6.0 KiB
Python
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"""Test functions for fftpack.helper module
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Copied from fftpack.helper by Pearu Peterson, October 2005
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"""
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import numpy as np
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from numpy import fft, pi
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from numpy.testing import assert_array_almost_equal
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class TestFFTShift:
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def test_definition(self):
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x = [0, 1, 2, 3, 4, -4, -3, -2, -1]
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y = [-4, -3, -2, -1, 0, 1, 2, 3, 4]
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assert_array_almost_equal(fft.fftshift(x), y)
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assert_array_almost_equal(fft.ifftshift(y), x)
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x = [0, 1, 2, 3, 4, -5, -4, -3, -2, -1]
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y = [-5, -4, -3, -2, -1, 0, 1, 2, 3, 4]
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assert_array_almost_equal(fft.fftshift(x), y)
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assert_array_almost_equal(fft.ifftshift(y), x)
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def test_inverse(self):
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for n in [1, 4, 9, 100, 211]:
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x = np.random.random((n,))
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assert_array_almost_equal(fft.ifftshift(fft.fftshift(x)), x)
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def test_axes_keyword(self):
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freqs = [[0, 1, 2], [3, 4, -4], [-3, -2, -1]]
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shifted = [[-1, -3, -2], [2, 0, 1], [-4, 3, 4]]
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assert_array_almost_equal(fft.fftshift(freqs, axes=(0, 1)), shifted)
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assert_array_almost_equal(fft.fftshift(freqs, axes=0),
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fft.fftshift(freqs, axes=(0,)))
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assert_array_almost_equal(fft.ifftshift(shifted, axes=(0, 1)), freqs)
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assert_array_almost_equal(fft.ifftshift(shifted, axes=0),
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fft.ifftshift(shifted, axes=(0,)))
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assert_array_almost_equal(fft.fftshift(freqs), shifted)
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assert_array_almost_equal(fft.ifftshift(shifted), freqs)
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def test_uneven_dims(self):
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""" Test 2D input, which has uneven dimension sizes """
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freqs = [
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[0, 1],
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[2, 3],
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[4, 5]
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]
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# shift in dimension 0
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shift_dim0 = [
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[4, 5],
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[0, 1],
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[2, 3]
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]
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assert_array_almost_equal(fft.fftshift(freqs, axes=0), shift_dim0)
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assert_array_almost_equal(fft.ifftshift(shift_dim0, axes=0), freqs)
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assert_array_almost_equal(fft.fftshift(freqs, axes=(0,)), shift_dim0)
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assert_array_almost_equal(fft.ifftshift(shift_dim0, axes=[0]), freqs)
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# shift in dimension 1
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shift_dim1 = [
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[1, 0],
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[3, 2],
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[5, 4]
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]
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assert_array_almost_equal(fft.fftshift(freqs, axes=1), shift_dim1)
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assert_array_almost_equal(fft.ifftshift(shift_dim1, axes=1), freqs)
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# shift in both dimensions
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shift_dim_both = [
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[5, 4],
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[1, 0],
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[3, 2]
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]
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assert_array_almost_equal(fft.fftshift(freqs, axes=(0, 1)), shift_dim_both)
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assert_array_almost_equal(fft.ifftshift(shift_dim_both, axes=(0, 1)), freqs)
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assert_array_almost_equal(fft.fftshift(freqs, axes=[0, 1]), shift_dim_both)
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assert_array_almost_equal(fft.ifftshift(shift_dim_both, axes=[0, 1]), freqs)
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# axes=None (default) shift in all dimensions
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assert_array_almost_equal(fft.fftshift(freqs, axes=None), shift_dim_both)
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assert_array_almost_equal(fft.ifftshift(shift_dim_both, axes=None), freqs)
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assert_array_almost_equal(fft.fftshift(freqs), shift_dim_both)
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assert_array_almost_equal(fft.ifftshift(shift_dim_both), freqs)
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def test_equal_to_original(self):
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""" Test the new (>=v1.15) and old implementations are equal (see #10073) """
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from numpy._core import arange, asarray, concatenate, take
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def original_fftshift(x, axes=None):
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""" How fftshift was implemented in v1.14"""
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tmp = asarray(x)
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ndim = tmp.ndim
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if axes is None:
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axes = list(range(ndim))
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elif isinstance(axes, int):
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axes = (axes,)
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y = tmp
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for k in axes:
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n = tmp.shape[k]
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p2 = (n + 1) // 2
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mylist = concatenate((arange(p2, n), arange(p2)))
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y = take(y, mylist, k)
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return y
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def original_ifftshift(x, axes=None):
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""" How ifftshift was implemented in v1.14 """
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tmp = asarray(x)
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ndim = tmp.ndim
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if axes is None:
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axes = list(range(ndim))
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elif isinstance(axes, int):
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axes = (axes,)
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y = tmp
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for k in axes:
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n = tmp.shape[k]
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p2 = n - (n + 1) // 2
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mylist = concatenate((arange(p2, n), arange(p2)))
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y = take(y, mylist, k)
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return y
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# create possible 2d array combinations and try all possible keywords
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# compare output to original functions
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for i in range(16):
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for j in range(16):
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for axes_keyword in [0, 1, None, (0,), (0, 1)]:
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inp = np.random.rand(i, j)
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assert_array_almost_equal(fft.fftshift(inp, axes_keyword),
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original_fftshift(inp, axes_keyword))
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assert_array_almost_equal(fft.ifftshift(inp, axes_keyword),
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original_ifftshift(inp, axes_keyword))
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class TestFFTFreq:
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def test_definition(self):
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x = [0, 1, 2, 3, 4, -4, -3, -2, -1]
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assert_array_almost_equal(9 * fft.fftfreq(9), x)
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assert_array_almost_equal(9 * pi * fft.fftfreq(9, pi), x)
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x = [0, 1, 2, 3, 4, -5, -4, -3, -2, -1]
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assert_array_almost_equal(10 * fft.fftfreq(10), x)
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assert_array_almost_equal(10 * pi * fft.fftfreq(10, pi), x)
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class TestRFFTFreq:
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def test_definition(self):
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x = [0, 1, 2, 3, 4]
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assert_array_almost_equal(9 * fft.rfftfreq(9), x)
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assert_array_almost_equal(9 * pi * fft.rfftfreq(9, pi), x)
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x = [0, 1, 2, 3, 4, 5]
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assert_array_almost_equal(10 * fft.rfftfreq(10), x)
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assert_array_almost_equal(10 * pi * fft.rfftfreq(10, pi), x)
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class TestIRFFTN:
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def test_not_last_axis_success(self):
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ar, ai = np.random.random((2, 16, 8, 32))
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a = ar + 1j * ai
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axes = (-2,)
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# Should not raise error
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fft.irfftn(a, axes=axes)
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