def test_invalid_a_b_setter(a):
"""Test setting invalid a, b values."""
ellipse = Ellipse(1, 1)
with pytest.raises(ValueError):
ellipse.a = a
with pytest.raises(ValueError):
ellipse.b = a
def test_invalid_a_b_constructor(a, b):
"""Test invalid a, b values in constructor."""
with pytest.raises(ValueError):
Ellipse(a, b)
with pytest.raises(ValueError):
Ellipse(b, a)
with pytest.raises(ValueError):
Ellipse(a, a)
def test_center():
"""Test getting and setting the center."""
ellipse = Ellipse(1, 2)
assert all(ellipse.center == (0, 0, 0))
center = (1, 1, 1)
ellipse.center = center
assert all(ellipse.center == center)
def test_a_b_getter_setter(a, b):
"""Test getter and setter for a and b."""
ellipse = Ellipse(a, b)
assert ellipse.a == a
assert ellipse.b == b
ellipse.a = a + 1
ellipse.b = b + 1
assert ellipse.a == a + 1
assert ellipse.b == b + 1
def test_set_area(a, b, area):
"""Test setting the area."""
ellipse = Ellipse(a, b)
original_area = ellipse.area
ellipse.area = area
assert ellipse.area == approx(area)
# Reset to original area
ellipse.area = original_area
assert ellipse.area == approx(original_area)
assert ellipse.a == approx(a)
assert ellipse.b == approx(b)
def test_moment_inertia(a, b, center):
ellipse = Ellipse(a, b)
assert np.all(np.asarray(ellipse.planar_moments_inertia) >= 0)
# We must set the center after construction so that the inertia tensor
# calculation is not shifted away from the origin.
ellipse.center = center
area = ellipse.area
expected = [np.pi / 4 * a * b**3, np.pi / 4 * a**3 * b, 0]
expected[0] += area * center[0]**2
expected[1] += area * center[1]**2
expected[2] = area * center[0] * center[1]
np.testing.assert_allclose(ellipse.planar_moments_inertia[:2],
expected[:2])
np.testing.assert_allclose(ellipse.planar_moments_inertia[2], expected[2])
assert ellipse.polar_moment_inertia == pytest.approx(sum(expected[:2]))
def test_perimeter(a, b):
"""Check surface area against an approximate formula."""
# Uses Ramanujan's approximation for the circumference of an ellipse:
# https://en.wikipedia.org/wiki/Ellipse#Circumference
ellipse = Ellipse(a, b)
b, a = sorted([a, b])
h = (a - b)**2 / (a + b)**2
approx_perimeter = np.pi * (a + b) * (1 + 3 * h /
(10 + np.sqrt(4 - 3 * h)))
assert ellipse.perimeter == pytest.approx(approx_perimeter, rel=1e-3)
assert ellipse.circumference == pytest.approx(approx_perimeter, rel=1e-3)
def test_perimeter_setter(value):
"""Test perimeter and circumference getter and setter."""
ellipse = Ellipse(1, 2)
perimeter_old = ellipse.perimeter
circumference_old = ellipse.circumference
ellipse.circumference = value
assert ellipse.circumference == approx(value)
assert ellipse.a == approx(1 * value / circumference_old)
assert ellipse.b == approx(2 * value / circumference_old)
ellipse = Ellipse(1, 2)
ellipse.perimeter = value
assert ellipse.perimeter == approx(value)
assert ellipse.a == approx(1 * value / perimeter_old)
assert ellipse.b == approx(2 * value / perimeter_old)
def test_eccentricity_ratio(a, k):
b = a * k
ellipse = Ellipse(a, b)
b, a = sorted([a, b])
expected = np.sqrt(1 - b**2 / a**2)
assert ellipse.eccentricity == pytest.approx(expected)
def test_maximal_centered_bounded_circle(a, b, center):
ellipse = Ellipse(a, b, center)
bounded_circle = ellipse.maximal_centered_bounded_circle
assert sphere_isclose(bounded_circle, Circle(min(a, b), center))
def test_minimal_bounding_circle(a, b, center):
ellipse = Ellipse(a, b, center)
bounding_circle = ellipse.minimal_bounding_circle
assert sphere_isclose(bounding_circle, Circle(max(a, b), center))
def test_distance_to_surface(a, b):
"""Test consistent volume and area for shape distance of an ellipse."""
theta = np.linspace(0, 2 * np.pi, 50000)
ellipse = Ellipse(a, b)
distance = ellipse.distance_to_surface(theta)
assert_distance_to_surface_2d(ellipse, theta, distance)
def test_repr():
ellipse = Ellipse(1, 2, [1, 2, 0])
assert str(ellipse), str(eval(repr(ellipse)))
def test_is_inside(x, y, center):
a, b = 1, 2
ellipse = Ellipse(a, b, center)
assert ellipse.is_inside([x, y, 0] + center).squeeze() == np.all(
np.array([x / a, y / b]) <= 1)
def test_inertia_tensor():
"""Test the inertia tensor calculation."""
ellipse = Ellipse(1, 2)
ellipse.center = (0, 0, 0)
assert np.sum(ellipse.inertia_tensor > 1e-6) == 1
assert ellipse.inertia_tensor[2, 2] == 5 * np.pi / 2
def test_eccentricity(a, b):
ellipse = Ellipse(a, b)
assert ellipse.eccentricity >= 0
def test_area_getter(a, b):
ellipse = Ellipse(1, 1)
ellipse.a = a
ellipse.b = b
assert ellipse.area == np.pi * a * b
def test_get_set_minimal_centered_bounding_ellipse_radius(a, b, center):
_test_get_set_minimal_bounding_sphere_radius(Ellipse(a, b, center), True)
def test_iq(a, b):
ellipse = Ellipse(a, b)
assert ellipse.iq <= 1