def sample(self, point, n_samples=1):
"""Sample from the Gamma distribution.
Sample from the Gamma distribution with parameters provided
by point. This gives n_samples points.
Parameters
----------
point : array-like, shape=[..., dim]
Point representing a Gamma distribution.
n_samples : int
Number of points to sample for each set of parameters in point.
Optional, default: 1.
Returns
-------
samples : array-like, shape=[..., n_samples]
Sample from the Gamma distributions.
"""
geomstats.errors.check_belongs(point, self)
point = gs.to_ndarray(point, to_ndim=2)
samples = []
for param in point:
sample = gs.array(
gamma.rvs(param[0],
loc=0,
scale=param[1] / param[0],
size=n_samples))
samples.append(sample)
return gs.squeeze(samples[0]) if len(point) == 1 else gs.stack(samples)
def predict(self, X, fuzzy_predictions=False):
"""Predict the labels for each data point.
Label each data point with the cluster having the nearest
centroid using metric distance.
Parameters
----------
X : array-like, shape=[..., n_features]
Input data.
Returns n
|7i0-o≥
-------
self : array-like, shape=[...,]
Array of predicted cluster indices for each sample.
"""
if self.centroids is None:
raise RuntimeError('fit needs to be called first.')
dists = gs.stack(
[self.metric.dist(centroid, X)
for centroid in self.centroids],
axis=1)
dists = gs.squeeze(dists)
if fuzzy_predictions:
dists[np.where(dists == 0)] = 0.00001
belongs = 1 / (dists * np.sum(1 / dists, axis=1)[:, None])
else:
belongs = gs.argmin(dists, -1)
return belongs
def maximum_likelihood_fit(data, loc=0, scale=1):
"""Estimate parameters from samples.
This a wrapper around scipy's maximum likelihood estimator to
estimate the parameters of a beta distribution from samples.
Parameters
----------
data : array-like, shape=[..., n_samples]
Data to estimate parameters from. Arrays of
different length may be passed.
loc : float
Location parameter of the distribution to estimate parameters
from. It is kept fixed during optimization.
Optional, default: 0.
scale : float
Scale parameter of the distribution to estimate parameters
from. It is kept fixed during optimization.
Optional, default: 1.
Returns
-------
parameter : array-like, shape=[..., 2]
Estimate of parameter obtained by maximum likelihood.
"""
data = gs.cast(data, gs.float32)
data = gs.to_ndarray(
gs.where(data == 1., 1. - EPSILON, data), to_ndim=2)
parameters = []
for sample in data:
param_a, param_b, _, _ = beta.fit(sample, floc=loc, fscale=scale)
parameters.append(gs.array([param_a, param_b]))
return parameters[0] if len(data) == 1 else gs.stack(parameters)
def path(t):
"""Generate parameterized function for geodesic curve.
Parameters
----------
t : array-like, shape=[n_points,]
Times at which to compute points of the geodesics.
"""
t = gs.array(t)
t = gs.cast(t, initial_tangent_vec.dtype)
t = gs.to_ndarray(t, to_ndim=1)
if point_type == "vector":
tangent_vecs = gs.einsum("i,...k->...ik", t,
initial_tangent_vec)
else:
tangent_vecs = gs.einsum("i,...kl->...ikl", t,
initial_tangent_vec)
points_at_time_t = [
self.exp(tv, pt) for tv, pt in zip(tangent_vecs, initial_point)
]
points_at_time_t = gs.stack(points_at_time_t, axis=0)
return (points_at_time_t[0]
if n_initial_conditions == 1 else points_at_time_t)
def belongs(self, point, atol=gs.atol):
"""Check if the point belongs to the manifold.
Check if an (n,n)-matrix is an orthogonal projector
onto a subspace of rank k.
Parameters
----------
point : array-like, shape=[..., n, n]
Point to be checked.
atol : int
Optional, default: backend atol.
Returns
-------
belongs : array-like, shape=[...,]
Boolean evaluating if point belongs to the Grassmannian.
"""
if not gs.all(self._check_square(point)):
raise ValueError('all points must be square.')
symm = Matrices.is_symmetric(point)
idem = self._check_idempotent(point, atol)
rank = self._check_rank(point, self.k, atol)
belongs = gs.all(gs.stack([symm, idem, rank], axis=0), axis=0)
return belongs
def regularize(self, point):
"""Regularize the point into the manifold's canonical representation.
Parameters
----------
point : array-like, shape=[..., {dim, [n_manifolds, dim_each]}]
Point to be regularized.
point_type : str, {'vector', 'matrix'}
Representation of point.
Optional, default: None.
Returns
-------
regularized_point : array-like,
shape=[..., {dim, [n_manifolds, dim_each]}]
Point in the manifold's canonical representation.
"""
point_type = self.default_point_type
if point_type == "vector":
intrinsic = self.metric.is_intrinsic(point)
regularized_point = self._iterate_over_manifolds(
"regularize", {"point": point}, intrinsic
)
regularized_point = gs.concatenate(regularized_point, axis=-1)
elif point_type == "matrix":
regularized_point = [
manifold_i.regularize(point[..., i, :])
for i, manifold_i in enumerate(self.manifolds)
]
regularized_point = gs.stack(regularized_point, axis=1)
return regularized_point
def projection(self, point):
"""Project a point in product embedding manifold on each manifold.
Parameters
----------
point : array-like, shape=[..., {dim, [n_manifolds, dim_each]}]
Point in embedding manifold.
Returns
-------
projected : array-like, shape=[..., {dim, [n_manifolds, dim_each]}]
Projected point.
"""
point_type = self.default_point_type
geomstats.errors.check_parameter_accepted_values(
point_type, "point_type", ["vector", "matrix"]
)
if point_type == "vector":
intrinsic = self.metric.is_intrinsic(point)
projected_point = self._iterate_over_manifolds(
"projection", {"point": point}, intrinsic
)
projected_point = gs.concatenate(projected_point, axis=-1)
elif point_type == "matrix":
projected_point = [
manifold_i.projection(point[..., i, :])
for i, manifold_i in enumerate(self.manifolds)
]
projected_point = gs.stack(projected_point, axis=-2)
return projected_point
def extrinsic_to_spherical(self, point_extrinsic):
"""Convert point from extrinsic to spherical coordinates.
Convert from the extrinsic coordinates, i.e. embedded in Euclidean
space of dim 3 to spherical coordinates in the hypersphere.
Spherical coordinates are defined from the north pole, i.e.
angles [0., 0.] correspond to point [0., 0., 1.].
Only implemented in dimension 2.
Parameters
----------
point_extrinsic : array-like, shape=[..., dim]
Point on the sphere, in extrinsic coordinates.
Returns
-------
point_spherical : array_like, shape=[..., dim + 1]
Point on the sphere, in spherical coordinates relative to the
north pole.
"""
if self.dim != 2:
raise NotImplementedError(
"The conversion from to extrinsic coordinates "
"spherical coordinates is implemented"
" only in dimension 2.")
theta = gs.arccos(point_extrinsic[..., -1])
x = point_extrinsic[..., 0]
y = point_extrinsic[..., 1]
phi = gs.arctan2(y, x)
phi = gs.where(phi < 0, phi + 2 * gs.pi, phi)
return gs.stack([theta, phi], axis=-1)
def _normalization_factor_odd_dim(self, variances):
"""Compute the normalization factor - odd dimension."""
dim = self.dim
half_dim = int((dim + 1) / 2)
area = 2 * gs.pi**half_dim / math.factorial(half_dim - 1)
comb = gs.comb(dim - 1, half_dim - 1)
erf_arg = gs.sqrt(variances / 2) * gs.pi
first_term = (area / (2**dim - 1) * comb *
gs.sqrt(gs.pi / (2 * variances)) * gs.erf(erf_arg))
def summand(k):
exp_arg = -((dim - 1 - 2 * k)**2) / 2 / variances
erf_arg_2 = (gs.pi * variances -
(dim - 1 - 2 * k) * 1j) / gs.sqrt(2 * variances)
sign = (-1.0)**k
comb_2 = gs.comb(k, dim - 1)
return sign * comb_2 * gs.exp(exp_arg) * gs.real(gs.erf(erf_arg_2))
if half_dim > 2:
sum_term = gs.sum(
gs.stack([summand(k)] for k in range(half_dim - 2)))
else:
sum_term = summand(0)
coef = area / 2 / erf_arg * gs.pi**0.5 * (-1.0)**(half_dim - 1)
return first_term + coef / 2**(dim - 2) * sum_term
def __init__(self, n):
dim = int(n * (n - 1) / 2)
super(SkewSymmetricMatrices, self).__init__(dim, n)
if n == 2:
self.basis = gs.array([[[0., -1.], [1., 0.]]])
elif n == 3:
self.basis = gs.array([
[[0., 0., 0.],
[0., 0., -1.],
[0., 1., 0.]],
[[0., 0., 1.],
[0., 0., 0.],
[-1., 0., 0.]],
[[0., -1., 0.],
[1., 0., 0.],
[0., 0., 0.]]])
else:
self.basis = gs.zeros((dim, n, n))
basis = []
for row in gs.arange(n - 1):
for col in gs.arange(row + 1, n):
basis.append(gs.array_from_sparse(
[(row, col), (col, row)], [1., -1.], (n, n)))
self.basis = gs.stack(basis)
def basis_representation(self, matrix_representation):
"""Calculate the coefficients of given matrix in the basis.
Compute a 1d-array that corresponds to the input matrix in the basis
representation.
Parameters
----------
matrix_representation : array-like, shape=[..., n, n]
Matrix.
Returns
-------
basis_representation : array-like, shape=[..., dim]
Representation in the basis.
"""
if self.n == 2:
return matrix_representation[..., 1, 0][..., None]
if self.n == 3:
vec = gs.stack([
matrix_representation[..., 2, 1],
matrix_representation[..., 0, 2],
matrix_representation[..., 1, 0]])
return gs.transpose(vec)
return gs.triu_to_vec(matrix_representation, k=1)
def test_exp_vectorization(self, dim, point_a, point_b):
metric = self.metric(dim)
dist_a_b = metric.exp(point_a, point_b)
result_vect = dist_a_b
result = [metric.exp(point_a, point_b[i]) for i in range(len(point_b))]
result = gs.stack(result, axis=0)
self.assertAllClose(result_vect, result)
dist_a_b = metric.exp(point_b, point_a)
result_vect = dist_a_b
result = [metric.exp(point_b[i], point_a) for i in range(len(point_b))]
result = gs.stack(result, axis=0)
self.assertAllClose(result_vect, result)
def ivp(state, _):
"""Reformat the initial value problem geodesic ODE."""
position, velocity = state[:self.dim], state[self.dim:]
state = gs.stack([position, velocity])
vel, acc = self.geodesic_equation(state, _)
eq = (vel, acc)
return gs.hstack(eq)
def maximum_likelihood_fit(data):
"""Estimate parameters from samples.
This is a wrapper around scipy's maximum likelihood estimator to
estimate the parameters of a gamma distribution from samples.
Parameters
----------
data : list or list of lists/arrays
Data to estimate parameters from. Lists of
different length may be passed.
Returns
-------
parameter : array-like, shape=[..., 2]
Estimate of parameter obtained by maximum likelihood.
"""
def is_nested(sample):
"""Check if sample contains an iterable."""
for el in sample:
try:
return iter(el)
except TypeError:
return False
if not is_nested(data):
data = [data]
parameters = []
for sample in data:
sample = gs.array(sample)
kappa, _, scale = gamma.fit(sample, floc=0)
nu = 1 / scale
parameters.append(gs.array([kappa, kappa / nu]))
return parameters[0] if len(data) == 1 else gs.stack(parameters)
def test_space_derivative(self, dim, n_points, n_discretized_curves,
n_sampling_points):
"""Test space derivative.
Check result on an example and vectorization.
"""
n_points = 3
dim = 3
srv_metric_r3 = SRVMetric(Euclidean(dim))
curve = gs.random.rand(n_points, dim)
result = srv_metric_r3.space_derivative(curve)
delta = 1 / n_points
d_curve_1 = (curve[1] - curve[0]) / delta
d_curve_2 = (curve[2] - curve[0]) / (2 * delta)
d_curve_3 = (curve[2] - curve[1]) / delta
expected = gs.squeeze(
gs.vstack((
gs.to_ndarray(d_curve_1, 2),
gs.to_ndarray(d_curve_2, 2),
gs.to_ndarray(d_curve_3, 2),
)))
self.assertAllClose(result, expected)
path_of_curves = gs.random.rand(n_discretized_curves,
n_sampling_points, dim)
result = srv_metric_r3.space_derivative(path_of_curves)
expected = []
for i in range(n_discretized_curves):
expected.append(srv_metric_r3.space_derivative(path_of_curves[i]))
expected = gs.stack(expected)
self.assertAllClose(result, expected)
def _normalization_factor_even_dim(self, variances):
"""Compute the normalization factor - even dimension."""
dim = self.dim
half_dim = (dim + 1) / 2
area = 2 * gs.pi**half_dim / math.gamma(half_dim)
def summand(k):
exp_arg = -((dim - 1 - 2 * k)**2) / 2 / variances
erf_arg_1 = (dim - 1 - 2 * k) * 1j / gs.sqrt(2 * variances)
erf_arg_2 = (gs.pi * variances -
(dim - 1 - 2 * k) * 1j) / gs.sqrt(2 * variances)
sign = (-1.0)**k
comb = gs.comb(dim - 1, k)
erf_terms = gs.imag(gs.erf(erf_arg_2) + gs.erf(erf_arg_1))
return sign * comb * gs.exp(exp_arg) * erf_terms
half_dim_2 = int((dim - 2) / 2)
if half_dim_2 > 0:
sum_term = gs.sum(gs.stack([summand(k)]
for k in range(half_dim_2)))
else:
sum_term = summand(0)
coef = (area * (-1.0)**half_dim_2 / 2**(dim - 2) *
gs.sqrt(gs.pi / 2 / variances))
return coef * sum_term
def predict(self, X):
"""Predict the labels for each data point.
Label each data point with the cluster having the nearest
centroid using metric distance.
Parameters
----------
X : array-like, shape=[..., n_features]
Input data.
Returns
-------
self : array-like, shape=[...,]
Array of predicted cluster indices for each sample.
"""
if self.centroids is None:
raise RuntimeError('fit needs to be called first.')
dists = gs.stack(
[self.metric.dist(centroid, X) for centroid in self.centroids],
axis=1)
dists = gs.squeeze(dists)
belongs = gs.argmin(dists, -1)
return belongs
def convert_to_planar_coordinates(self, points):
"""Convert polar coordinates to spherical one."""
coords_r, coords_theta = self.convert_to_polar_coordinates(points)
coords_x = coords_r * gs.cos(coords_theta)
coords_y = coords_r * gs.sin(coords_theta)
planar_coords = gs.transpose(gs.stack((coords_x, coords_y)))
return planar_coords
def random_point(self, n_samples=1, bound=1.0):
"""Sample in the product space from the uniform distribution.
Parameters
----------
n_samples : int, optional
Number of samples.
bound : float
Bound of the interval in which to sample for non compact manifolds.
Optional, default: 1.
Returns
-------
samples : array-like, shape=[..., {dim, [n_manifolds, dim_each]}]
Points sampled on the hypersphere.
"""
point_type = self.default_point_type
geomstats.errors.check_parameter_accepted_values(
point_type, "point_type", ["vector", "matrix"]
)
if point_type == "vector":
data = self.manifolds[0].random_point(n_samples, bound)
if len(self.manifolds) > 1:
for space in self.manifolds[1:]:
samples = space.random_point(n_samples, bound)
data = gs.concatenate([data, samples], axis=-1)
return data
point = [space.random_point(n_samples, bound) for space in self.manifolds]
samples = gs.stack(point, axis=-2)
return samples
def regularize(self, point, point_type=None):
"""Regularize the point into the manifold's canonical representation.
Parameters
----------
point : array-like, shape=[..., {dim, [dim_2, dim_2]}]
Point to be regularized.
point_type : str, {'vector', 'matrix'}
Representation of point.
Returns
-------
regularized_point : array-like, shape=[..., {dim, [dim_2, dim_2]}]
Point in the manifold's canonical representation.
"""
if point_type is None:
point_type = self.default_point_type
geomstats.errors.check_parameter_accepted_values(
point_type, 'point_type', ['vector', 'matrix'])
if point_type == 'vector':
intrinsic = self.metric.is_intrinsic(point)
regularized_point = self._iterate_over_manifolds(
'regularize', {'point': point}, intrinsic)
regularized_point = gs.hstack(regularized_point)
elif point_type == 'matrix':
regularized_point = [
manifold_i.regularize(point[:, i])
for i, manifold_i in enumerate(self.manifolds)]
regularized_point = gs.stack(regularized_point, axis=1)
return regularized_point
def projection_to_tangent_space(self, vector, base_point):
"""Project a vector in the tangent space.
Project a vector in Minkowski space
on the tangent space of the hyperbolic space at a base point.
Parameters
----------
vector : array-like, shape=[n_samples, n_disks, dimension + 1]
base_point : array-like, shape=[n_samples, n_disks, dimension + 1]
Returns
-------
tangent_vec : array-like, shape=[n_samples, n_disks, dimension + 1]
"""
n_disks = base_point.shape[1]
hyperbolic_space = Hyperbolic(dimension=2, point_type=self.point_type)
tangent_vec = gs.stack([
Hyperbolic.projection_to_tangent_space(
self=hyperbolic_space,
vector=vector[:, i_disk, :],
base_point=base_point[:, i_disk, :])
for i_disk in range(n_disks)
],
axis=1)
return tangent_vec
def random_uniform(self, n_samples, point_type=None):
"""Sample in the product space from the uniform distribution.
Parameters
----------
n_samples : int, optional
Number of samples.
point_type : str, {'vector', 'matrix'}
Representation of point.
Returns
-------
samples : array-like, shape=[..., dim + 1]
Points sampled on the hypersphere.
"""
if point_type is None:
point_type = self.default_point_type
geomstats.errors.check_parameter_accepted_values(
point_type, 'point_type', ['vector', 'matrix'])
if point_type == 'vector':
data = self.manifolds[0].random_uniform(n_samples)
if len(self.manifolds) > 1:
for space in self.manifolds[1:]:
samples = space.random_uniform(n_samples)
data = gs.concatenate([data, samples], axis=-1)
return data
point = [
space.random_uniform(n_samples)
for space in self.manifolds]
samples = gs.stack(point, axis=1)
return samples
def test_exp_vectorization(self):
point = gs.array([[1., 1.], [1., 1.]])
tangent_vec = gs.array([[2., 1.], [2., 1.]])
result = self.metric.exp(tangent_vec, point)
point = point[0]
tangent_vec = tangent_vec[0]
circle_center = point[0] + point[1] * tangent_vec[1] / tangent_vec[0]
circle_radius = gs.sqrt((circle_center - point[0])**2 + point[1]**2)
moebius_d = 1
moebius_c = 1 / (2 * circle_radius)
moebius_b = circle_center - circle_radius
moebius_a = (circle_center + circle_radius) * moebius_c
point_complex = point[0] + 1j * point[1]
tangent_vec_complex = tangent_vec[0] + 1j * tangent_vec[1]
point_moebius = 1j * (moebius_d * point_complex - moebius_b)\
/ (moebius_c * point_complex - moebius_a)
tangent_vec_moebius = -1j * tangent_vec_complex * (
1j * moebius_c * point_moebius + moebius_d)**2
end_point_moebius = point_moebius * gs.exp(
tangent_vec_moebius / point_moebius)
end_point_complex = (moebius_a * 1j * end_point_moebius + moebius_b)\
/ (moebius_c * 1j * end_point_moebius + moebius_d)
end_point_expected = gs.hstack(
[np.real(end_point_complex),
np.imag(end_point_complex)])
expected = gs.stack([end_point_expected, end_point_expected])
self.assertAllClose(result, expected)
def intrinsic_to_extrinsic_coords(point_intrinsic):
"""Convert point from intrinsic to extrensic coordinates.
Convert the parameterization of a point in the hyperbolic space
from its intrinsic coordinates, to its extrinsic coordinates
in Minkowski space.
Parameters
----------
point_intrinsic : array-like, shape=[..., n_disk, dim]
Point in intrinsic coordinates.
Returns
-------
point_extrinsic : array-like, shape=[..., n_disks, dim + 1]
Point in extrinsic coordinates.
"""
n_disks = point_intrinsic.shape[1]
point_extrinsic = gs.stack(
[
_Hyperbolic.change_coordinates_system(
point_intrinsic[:, i_disk, ...], "intrinsic", "extrinsic")
for i_disk in range(n_disks)
],
axis=1,
)
return point_extrinsic
def from_vector(vec, dtype=gs.float32):
"""Convert a vector into a symmetric matrix.
Parameters
----------
vec : array-like, shape=[..., n(n+1)/2]
Vector.
dtype : dtype, {gs.float32, gs.float64}
Data type object to use for the output.
Optional. Default: gs.float32.
Returns
-------
mat : array-like, shape=[..., n, n]
Symmetric matrix.
"""
vec_dim = vec.shape[-1]
mat_dim = (gs.sqrt(8. * vec_dim + 1) - 1) / 2
if mat_dim != int(mat_dim):
raise ValueError('Invalid input dimension, it must be of the form'
'(n_samples, n * (n + 1) / 2)')
mat_dim = int(mat_dim)
shape = (mat_dim, mat_dim)
mask = 2 * gs.ones(shape) - gs.eye(mat_dim)
indices = list(zip(*gs.triu_indices(mat_dim)))
vec = gs.cast(vec, dtype)
upper_triangular = gs.stack(
[gs.array_from_sparse(indices, data, shape) for data in vec])
mat = Matrices.to_symmetric(upper_triangular) * mask
return mat
def random_uniform(self, n_samples, point_type=None):
"""Sample in the product space from the uniform distribution.
Parameters
----------
n_samples : int, optional
Number of samples.
point_type : str, {'vector', 'matrix'}
Representation of point.
Returns
-------
samples : array-like, shape=[n_samples, dimension + 1]
Points sampled on the hypersphere.
"""
if point_type is None:
point_type = self.default_point_type
assert point_type in ['vector', 'matrix']
if point_type == 'vector':
data = self.manifolds[0].random_uniform(n_samples)
if len(self.manifolds) > 1:
for i, space in enumerate(self.manifolds[1:]):
data = gs.concatenate(
[data, space.random_uniform(n_samples)], axis=1)
return data
else:
point = [
space.random_uniform(n_samples) for space in self.manifolds
]
return gs.stack(point, axis=1)
def to_tangent(self, vector, base_point):
"""Project a vector in the tangent space.
Project a vector in Minkowski space
on the tangent space of the hyperbolic space at a base point.
Parameters
----------
vector : array-like, shape=[..., n_disks, dim + 1]
Vector.
base_point : array-like, shape=[..., n_disks, dim + 1]
Base point.
Returns
-------
tangent_vec : array-like, shape=[..., n_disks, dim + 1]
Tangent vector at base point.
"""
n_disks = base_point.shape[1]
hyperbolic_space = Hyperboloid(2, self.coords_type)
tangent_vec = gs.stack([hyperbolic_space.to_tangent(
vector=vector[..., i_disk, :],
base_point=base_point[..., i_disk, :])
for i_disk in range(n_disks)], axis=1)
return tangent_vec
def test_split_horizontal_vertical(self, times, n_discretized_curves,
curve_a, curve_b):
"""Test split horizontal vertical.
Check that horizontal and vertical parts of any tangent
vector are othogonal with respect to the SRVMetric inner
product, and check vectorization.
"""
srv_metric_r3 = SRVMetric(r3)
quotient_srv_metric_r3 = DiscreteCurves(
ambient_manifold=r3).quotient_square_root_velocity_metric
geod = srv_metric_r3.geodesic(initial_curve=curve_a, end_curve=curve_b)
geod = geod(times)
tangent_vec = n_discretized_curves * (geod[1, :, :] - geod[0, :, :])
(
tangent_vec_hor,
tangent_vec_ver,
_,
) = quotient_srv_metric_r3.split_horizontal_vertical(
tangent_vec, curve_a)
result = srv_metric_r3.inner_product(tangent_vec_hor, tangent_vec_ver,
curve_a)
expected = 0.0
self.assertAllClose(result, expected, atol=1e-4)
tangent_vecs = n_discretized_curves * (geod[1:] - geod[:-1])
_, _, result = quotient_srv_metric_r3.split_horizontal_vertical(
tangent_vecs, geod[:-1])
expected = []
for i in range(n_discretized_curves - 1):
_, _, res = quotient_srv_metric_r3.split_horizontal_vertical(
tangent_vecs[i], geod[i])
expected.append(res)
expected = gs.stack(expected)
self.assertAllClose(result, expected)
def sample(self, point, n_samples=1):
"""Sample from the beta distribution.
Sample from the beta distribution with parameters provided by point.
Parameters
----------
point : array-like, shape=[..., 2]
Point representing a beta distribution.
n_samples : int
Number of points to sample with each pair of parameters in point.
Optional, default: 1.
Returns
-------
samples : array-like, shape=[..., n_samples]
Sample from beta distributions.
"""
geomstats.errors.check_belongs(point, self)
point = gs.to_ndarray(point, to_ndim=2)
samples = []
for param_a, param_b in point:
samples.append(gs.array(
beta.rvs(param_a, param_b, size=n_samples)))
return samples[0] if len(point) == 1 else gs.stack(samples)
def regularize(self, point, point_type=None):
"""Regularize the point into the manifold's canonical representation.
Parameters
----------
point : array-like, shape=[n_samples, dim]
or shape=[n_samples, dim_2, dim_2]
Point to be regularized.
point_type : str, {'vector', 'matrix'}
Representation of point.
Returns
-------
regularized_point : array-like, shape=[n_samples, dim]
or shape=[n_samples, dim_2, dim_2]
Point in the manifold's canonical representation.
"""
if point_type is None:
point_type = self.default_point_type
assert point_type in ['vector', 'matrix']
if point_type == 'vector':
point = gs.to_ndarray(point, to_ndim=2)
intrinsic = self.metric.is_intrinsic(point)
regularized_point = self._iterate_over_manifolds(
'regularize', {'point': point}, intrinsic)
regularized_point = gs.hstack(regularized_point)
elif point_type == 'matrix':
regularized_point = [
manifold_i.regularize(point[:, i])
for i, manifold_i in enumerate(self.manifolds)]
regularized_point = gs.stack(regularized_point, axis=1)
return regularized_point
