Add test for sphere and torus

Fix numerical approximations inconsistencies with dim fraction exponent when generating points as grid on torus
Add notes in doc regarding the torus versions use cases

2 files changed, 5 insertions, 4 deletions

diff --git a/src/python/gudhi/datasets/generators/_points.cc b/src/python/gudhi/datasets/generators/_points.cc
index 6bbdf284..3d38ff90 100644
--- a/src/python/gudhi/datasets/generators/_points.cc
+++ b/src/python/gudhi/datasets/generators/_points.cc
@@ -48,6 +48,10 @@ py::array_t<double> generate_points_on_sphere(size_t n_samples, int ambient_dim,
 
 py::array_t<double> generate_points_on_torus(size_t n_samples, int dim, std::string sample) {
 
+    if ( (sample != "random") && (sample != "grid")) {
+        throw pybind11::value_error("This sample type is not supported");
+    }
+
     std::vector<typename Kern::Point_d> points_generated;
 
     {
diff --git a/src/python/gudhi/datasets/generators/points.py b/src/python/gudhi/datasets/generators/points.py
index 3870dea6..daada486 100644
--- a/src/python/gudhi/datasets/generators/points.py
+++ b/src/python/gudhi/datasets/generators/points.py
@@ -23,7 +23,7 @@ def _generate_random_points_on_torus(n_samples, dim):
 def _generate_grid_points_on_torus(n_samples, dim):
     
     # Generate points on a dim-torus as a grid
-    n_samples_grid = int(n_samples**(1./dim))
+    n_samples_grid = int((n_samples+.5)**(1./dim)) # add .5 to avoid rounding down with numerical approximations
     alpha = np.linspace(0, 2*np.pi, n_samples_grid, endpoint=False)
     
     array_points_inter = np.column_stack([np.cos(alpha), np.sin(alpha)])
@@ -45,12 +45,9 @@ def torus(n_samples, dim, sample='random'):
     """
     if sample == 'random':
         # Generate points randomly
-        print("Sample is random")
         return _generate_random_points_on_torus(n_samples, dim)
     elif sample == 'grid':
         # Generate points on a grid
-        print("Sample is grid")
         return _generate_grid_points_on_torus(n_samples, dim)
     else:
         raise ValueError("Sample type '{}' is not supported".format(sample))
-        return