def test_sample_closed_starts_and_ends_at_min_anomaly_if_in_range_and_no_max_given(
min_nu, ecc
):
result = sample_closed(min_nu, ecc)
assert_quantity_allclose(result[0], min_nu, atol=1e-14 * u.rad)
assert_quantity_allclose(result[-1], min_nu, atol=1e-14 * u.rad)
def sample(self, values=100, *, min_anomaly=None, max_anomaly=None):
r"""Samples an orbit to some specified time values.
.. versionadded:: 0.8.0
Parameters
----------
values : int
Number of interval points (default to 100).
min_anomaly, max_anomaly : ~astropy.units.Quantity, optional
Anomaly limits to sample the orbit.
For elliptic orbits the default will be :math:`E \in \left[0, 2 \pi \right]`,
and for hyperbolic orbits it will be :math:`\nu \in \left[-\nu_c, \nu_c \right]`,
where :math:`\nu_c` is either the current true anomaly
or a value that corresponds to :math:`r = 3p`.
Returns
-------
positions: ~astropy.coordinates.CartesianRepresentation
Array of x, y, z positions.
Notes
-----
When specifying a number of points, the initial and final
position is present twice inside the result (first and
last row). This is more useful for plotting.
Examples
--------
>>> from astropy import units as u
>>> from poliastro.examples import iss
>>> iss.sample() # doctest: +ELLIPSIS
<CartesianRepresentation (x, y, z) in km ...
>>> iss.sample(10) # doctest: +ELLIPSIS
<CartesianRepresentation (x, y, z) in km ...
"""
if self.ecc < 1:
nu_values = sample_closed(
min_anomaly if min_anomaly is not None else self.nu,
self.ecc,
max_anomaly,
values,
)
else:
nu_values = self._sample_open(values, min_anomaly, max_anomaly)
n = nu_values.shape[0]
rr, vv = coe2rv_many(
np.tile(self.attractor.k, n),
np.tile(self.p, n),
np.tile(self.ecc, n),
np.tile(self.inc, n),
np.tile(self.raan, n),
np.tile(self.argp, n),
nu_values,
)
cartesian = CartesianRepresentation(
rr, differentials=CartesianDifferential(vv, xyz_axis=1), xyz_axis=1
)
return cartesian
def test_sample_closed_starts_at_min_anomaly_if_in_range(min_nu, ecc, max_nu):
result = sample_closed(min_nu, ecc, max_nu)
assert_quantity_allclose(result[0], min_nu, atol=1e-15 * u.rad)
def test_sample_closed_is_always_between_minus_pi_and_pi(min_nu, ecc, max_nu):
result = sample_closed(min_nu, ecc, max_nu)
assert ((-np.pi * u.rad <= result) & (result <= np.pi * u.rad)).all()
