CHG: Keep last edge instad of first one

Author: kilianvolmer

cpp/memilio/mobility/graph.h

@@ -508,7 +508,7 @@ class GraphBuilder
      * 
      * Sorts the edges and optionally removes duplicate edges (same start and end node indices).
      * Wihout dupplicate removal, multiple edges between the same nodes are allowed and the order of insertion is stable.
-     * @param make_unique If true, duplicate edges are removed. The first added edge is kept!
+     * @param make_unique If true, duplicate edges are removed. The last added edge is kept!
      * @return Graph<NodePropertyT, EdgePropertyT> The constructed graph.
      */
     Graph<NodeProperty, EdgeProperty> build(bool make_unique = false)
@@ -540,42 +540,30 @@ class GraphBuilder
      * @brief Remove duplicate edges from a sorted edge vector.
      * 
      * Copies all the unique edges to a new vector and replaces the original edge vector with it. Unique means that
-     * the start and end node indices are unique. Other edge properties are not checked and may get lost. Only the first 
+     * the start and end node indices are unique. Other edge properties are not checked and may get lost. Only the last 
      * edge in the vector is kept.
      */
     void remove_duplicate_edges()
     {
         std::vector<Edge<EdgePropertyT>> unique_edges;
         unique_edges.reserve(m_edges.size());
-        std::ranges::unique_copy(m_edges, std::back_inserter(unique_edges), [](auto&& e1, auto&& e2) {
+        auto curr_elem = m_edges.begin();
+        auto next_elem = std::adjacent_find(curr_elem, m_edges.end(), [](auto&& e1, auto&& e2) {
             return e1.start_node_idx == e2.start_node_idx && e1.end_node_idx == e2.end_node_idx;
         });
-        m_edges = std::move(unique_edges);
-    }
-
-    /**
-     * @brief Remove duplicate edges from a sorted edge vector.
-     * 
-     * Copies all the unique edges to a new vector and replaces the original edge vector with it. Unique means that
-     * the start and end node indices are unique. Other edge properties are not checked and may get lost. Only the first 
-     * edge in the vector is kept.
-     */
-    void remove_double_edges()
-    {
-        std::vector<Edge<EdgePropertyT>> unique_edges;
-        unique_edges.reserve(m_edges.size());
-        auto curr_elem = m_edges.begin();
-        auto next_elem = std::adjacent_find(curr_elem, m_edges.end(), is_equal);
         while (next_elem != m_edges.end()) {
             std::copy(curr_elem, next_elem, std::back_inserter(unique_edges));
             curr_elem = next_elem;
-            while (is_equal(*curr_elem, *next_elem) && next_elem != m_edges.end()) {
+            while ((*curr_elem).start_node_idx == (*next_elem).start_node_idx &&
+                   (*curr_elem).end_node_idx == (*next_elem).end_node_idx && next_elem != m_edges.end()) {
                 next_elem = next(next_elem);
             }
             curr_elem = prev(next_elem);
             std::copy(curr_elem, next(curr_elem), std::back_inserter(unique_edges));
             curr_elem = next(curr_elem);
-            next_elem = std::adjacent_find(curr_elem, m_edges.end(), is_equal);
+            next_elem = std::adjacent_find(curr_elem, m_edges.end(), [](auto&& e1, auto&& e2) {
+                return e1.start_node_idx == e2.start_node_idx && e1.end_node_idx == e2.end_node_idx;
+            });
         }
         std::copy(curr_elem, next_elem, std::back_inserter(unique_edges));
         m_edges = std::move(unique_edges);

cpp/tests/test_graph.cpp

@@ -375,9 +375,8 @@ TEST(TestGraphBuilder, Build_unique)
 
     EXPECT_EQ(g.nodes().size(), 3);
     EXPECT_EQ(g.edges().size(), 3);
-    for (const auto& e : g.edges()) {
-        EXPECT_EQ(e.property, 100);
-    }
+    // The last added edge is kept:
+    EXPECT_EQ(g.edges()[1].property, 200);
 }
 
 namespace

docs/source/cpp/graph_metapop.rst

@@ -195,7 +195,7 @@ The following steps detail how to configure and execute a graph simulation:
 
     Usually, there should be no duplicate edges in your input. If this is not certain, the ``GraphBuilder`` can also remove duplicates.
     Here, duplicate means that the start and end node are the same. The parameters in the edge will not be compared. 
-    When duplicates are found, only the **first** inserted edge is kept, all subsequent edges are discarded: 
+    When duplicates are found, only the **last** inserted edge is kept, all previous edges are discarded: 
 
     .. code-block:: cpp
 
@@ -208,24 +208,6 @@ The following steps detail how to configure and execute a graph simulation:
         auto graph = builder.build(true);
         // graph contains the edges (0, 1, 100) and (1, 0, 100)
 
-    To sum this up:
-    
-    .. list-table::
-    :header-rows: 1
-
-    * -  
-      - ``graph.add_edge``  
-      - ``GraphBuilder.add_edge``
-    * - Sorting  
-      - Always
-      - Only when graph is built      
-    * - Duplicate deletion
-      - Always
-      - Only when activated on insertion
-    * - Keeps 
-      - last duplicate
-      - first duplicate
-
 
 5. **Initialize and Advance the Mobility Simulation:**