Use boundary_opposite_vertex_simplex_range instead of boundary_simplex_range in alpha

1 files changed, 3 insertions, 10 deletions

diff --git a/src/Alpha_complex/include/gudhi/Alpha_complex.h b/src/Alpha_complex/include/gudhi/Alpha_complex.h
index b1a9407b..5a0f0643 100644
--- a/src/Alpha_complex/include/gudhi/Alpha_complex.h
+++ b/src/Alpha_complex/include/gudhi/Alpha_complex.h
@@ -464,7 +464,8 @@ class Alpha_complex {
     using Vertex_handle = typename SimplicialComplexForAlpha::Vertex_handle;
 
     // ### Foreach Tau face of Sigma
-    for (auto f_boundary : complex.boundary_simplex_range(f_simplex)) {
+    for (auto face_opposite_vertex : complex.boundary_opposite_vertex_simplex_range(f_simplex)) {
+      auto f_boundary = face_opposite_vertex.first;
 #ifdef DEBUG_TRACES
       std::clog << " | --------------------------------------------------\n";
       std::clog << " | Tau ";
@@ -485,16 +486,8 @@ class Alpha_complex {
 #endif  // DEBUG_TRACES
         // ### Else
       } else {
-        // Find which vertex of f_simplex is missing in f_boundary. We could actually write a variant of boundary_simplex_range that gives pairs (f_boundary, vertex). We rely on the fact that simplex_vertex_range is sorted.
-        auto longlist = complex.simplex_vertex_range(f_simplex);
-        auto shortlist = complex.simplex_vertex_range(f_boundary);
-        auto longiter = std::begin(longlist);
-        auto shortiter = std::begin(shortlist);
-        auto enditer = std::end(shortlist);
-        while(shortiter != enditer && *longiter == *shortiter) { ++longiter; ++shortiter; }
-        Vertex_handle extra = *longiter;
         auto const& cache=get_cache(complex, f_boundary);
-        bool is_gab = kernel_.is_gabriel(cache, get_point_(extra));
+        bool is_gab = kernel_.is_gabriel(cache, get_point_(face_opposite_vertex.second));
 #ifdef DEBUG_TRACES
         std::clog << " | Tau is_gabriel(Sigma)=" << is_gab << " - vertexForGabriel=" << extra << std::endl;
 #endif  // DEBUG_TRACES