def test_fourier_interpolate_transpose_symmetry(nx, ny, fine_nx, fine_ny):
topography = Topography(np.random.random((nx, ny)),
physical_sizes=(1., 1.5))
interp = topography.interpolate_fourier((fine_nx, fine_ny))
interp_t = topography.transpose().interpolate_fourier(
(fine_ny, fine_nx)).transpose()
np.testing.assert_allclose(interp.heights(), interp_t.heights())
def test_fourier_interpolate_nyquist(plot=False):
# asserts that the interpolation follows the "minimal-osciallation"
# assumption for the nyquist frequency
topography = Topography(np.array([[1], [-1]]), physical_sizes=(1., 1.))
interpolated_topography = topography.interpolate_fourier((64, 1))
if plot:
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
x, y = topography.positions()
ax.plot(x.flat, topography.heights().flat, "+")
x, y = interpolated_topography.positions()
ax.plot(x.flat, interpolated_topography.heights().flat, "-")
fig.show()
x, y = interpolated_topography.positions()
np.testing.assert_allclose(interpolated_topography.heights(),
np.cos(2 * np.pi * x), atol=1e-14)
