def test_center(self):
"""Test that _centered method is compatible with shift/unshift"""
shape = (5, 2)
a0 = np.arange(10).reshape(shape)
a_pad = fft._pad(a0, (9, 11))
truth = [[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 2, 3, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 4, 5, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 6, 7, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 8, 9, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
assert_array_equal(a_pad, truth)
a_shift = np.fft.ifftshift(a_pad)
truth = [[4, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[6, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[8, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[2, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
assert_array_equal(a_shift, truth)
# Shifting back should give us a_pad again
a_shift_back = np.fft.fftshift(a_shift)
assert_array_equal(a_shift_back, a_pad)
# _centered should undo the padding, returning the original array
a_final = fft._centered(a_pad, shape)
assert_array_equal(a_final, a0)
def test_shift(self):
"""Test that padding and fft shift/unshift are consistent"""
a0 = np.ones((1, 1))
a_pad = fft._pad(a0, (5, 4))
truth = [
[0.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 1.0, 0.0],
[0.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0],
]
assert_array_equal(a_pad, truth)
a_shift = np.fft.ifftshift(a_pad)
truth = [
[1.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0],
]
assert_array_equal(a_shift, truth)
# Shifting back should give us a_pad again
a_shift_back = np.fft.fftshift(a_shift)
assert_array_equal(a_shift_back, a_pad)