Some documentation and examples

3 files changed, 60 insertions, 0 deletions

diff --git a/src/Collapse/example/CMakeLists.txt b/src/Collapse/example/CMakeLists.txt
new file mode 100644
index 00000000..6cf3bf07
--- /dev/null
+++ b/src/Collapse/example/CMakeLists.txt
@@ -0,0 +1,10 @@
+project(Edge_collapse_examples)
+
+# Point cloud
+add_executable ( Edge_collapse_example_basic edge_collapse_basic_example.cpp )
+
+if (TBB_FOUND)
+  target_link_libraries(Edge_collapse_example_basic ${TBB_LIBRARIES})
+endif()
+
+add_test(NAME Edge_collapse_example_basic COMMAND $<TARGET_FILE:Edge_collapse_example_basic>)
diff --git a/src/Collapse/example/edge_collapse_basic_example.cpp b/src/Collapse/example/edge_collapse_basic_example.cpp
new file mode 100644
index 00000000..a154c6bb
--- /dev/null
+++ b/src/Collapse/example/edge_collapse_basic_example.cpp
@@ -0,0 +1,45 @@
+#include <gudhi/Flag_complex_sparse_matrix.h>
+
+#include <iostream>
+#include <vector>
+
+int main() {
+  // Type definitions
+  using Filtration_value = float;
+  using Vertex_handle = short;
+  using Flag_complex_sparse_matrix = Gudhi::collapse::Flag_complex_sparse_matrix<Vertex_handle, Filtration_value>;
+  using Filtered_edge = Flag_complex_sparse_matrix::Filtered_edge;
+  using Filtered_edge_list = std::vector<Filtered_edge>;
+  using Edge = Flag_complex_sparse_matrix::Edge;
+
+  //  1   2
+  //  o---o
+  //  |\ /|
+  //  | x |
+  //  |/ \|
+  //  o---o
+  //  0   3
+  Filtered_edge_list graph = {{{0, 1}, 1.},
+                              {{1, 2}, 1.},
+                              {{2, 3}, 1.},
+                              {{3, 0}, 1.},
+                              {{0, 2}, 2.},
+                              {{1, 3}, 2.}};
+
+  Flag_complex_sparse_matrix flag_complex_sparse_matrix(graph);
+
+  Filtered_edge_list collapse_edges;
+  // Retrieve collapse edges from the output iterator
+  flag_complex_sparse_matrix.filtered_edge_collapse(
+    [&collapse_edges](std::pair<Vertex_handle, Vertex_handle> edge, Filtration_value filtration) {
+        collapse_edges.push_back({edge, filtration});
+      });
+
+  for (Filtered_edge filtered_edge_from_collapse : collapse_edges) {
+    Edge edge_from_collapse = std::get<0>(filtered_edge_from_collapse);
+    std::cout << "fn[" << std::get<0>(edge_from_collapse) << ", " << std::get<1>(edge_from_collapse) << "] = "
+              << std::get<1>(filtered_edge_from_collapse) << std::endl;
+  }
+
+  return 0;
+}
diff --git a/src/Collapse/example/edge_collapse_example_basic.txt b/src/Collapse/example/edge_collapse_example_basic.txt
new file mode 100644
index 00000000..acecacaf
--- /dev/null
+++ b/src/Collapse/example/edge_collapse_example_basic.txt
@@ -0,0 +1,5 @@
+fn[0, 1] = 1
+fn[1, 2] = 1
+fn[2, 3] = 1
+fn[3, 0] = 1
+fn[0, 2] = 2