Merge pull request #127 from stdgraph/algorithms/cc

merge CC code into master

Author: kdeweese

data/cc_directed.csv

@@ -0,0 +1,22 @@
+From,To,Distance
+A,B,1
+B,C,1
+C,D,1
+D,A,1
+B,E,1
+E,F,1
+F,G,1
+G,H,1
+H,E,1
+G,Q,1
+Q,N,1
+N,O,1
+O,P,1
+P,M,1
+M,R,1
+R,H,1
+J,R,1
+J,K,1
+K,L,1
+L,I,1
+I,J,1

data/cc_undirected.csv

@@ -0,0 +1,15 @@
+From,To,Distance
+A,H,1
+H,A,1
+B,C,1
+C,B,1
+B,F,1
+F,B,1
+B,G,1
+G,B,1
+C,F,1
+F,C,1
+D,E,1
+E,D,1
+H,I,1
+I,H,1

include/graph/algorithm/connected_components.hpp

@@ -0,0 +1,115 @@
+/**
+ * @file connected_components.hpp
+ * 
+ * @brief Single-Source Shortest paths and shortest sistances algorithms using Dijkstra & 
+ * Bellman-Ford algorithms.
+ * 
+ * @copyright Copyright (c) 2022
+ * 
+ * SPDX-License-Identifier: BSL-1.0
+ *
+ * @authors
+ *   Andrew Lumsdaine
+ *   Phil Ratzloff
+ *   Kevin Deweese
+ */
+
+#include "graph/graph.hpp"
+#include "graph/views/incidence.hpp"
+
+#ifndef GRAPH_CC_HPP
+#  define GRAPH_CC_HPP
+
+namespace std::graph {
+
+template <adjacency_list G,
+          adjacency_list GT,
+          ranges::random_access_range Component>
+requires ranges::random_access_range<vertex_range_t<G>> && integral<vertex_id_t<G>>
+void kosaraju(G&&            g,        // graph
+              GT&&           g_t,      // graph transpose
+              Component&     component // out: strongly connected component assignment
+
+) {
+  size_t N(size(vertices(g)));
+  std::vector<bool> visited(N, false);
+  using CT = typename std::decay<decltype(*component.begin())>::type;
+  std::fill(component.begin(), component.end(), std::numeric_limits<CT>::max());
+  std::vector<vertex_id_t<G>> order;
+  
+  for (auto&& [uid, u] : views::vertexlist(g)) {
+    if (visited[uid]) {
+        continue;
+    }
+    visited[uid] = true;
+    std::stack<vertex_id_t<G>> active;
+    active.push(uid);
+    auto dfs = std::graph::views::sourced_edges_depth_first_search(g, uid);
+    for (auto&& [vid, wid, vw] : dfs) {
+        while (vid != active.top()) {
+          order.push_back(active.top());
+          active.pop();
+        }
+        if (visited[wid]) {
+          dfs.cancel(cancel_search::cancel_branch);
+        }
+        else {
+          active.push(wid);
+          visited[wid] = true;
+        }
+    }
+    while (!active.empty()) {
+      order.push_back(active.top());
+      active.pop();
+    }
+  }
+
+  size_t cid = 0;
+  std::ranges::reverse_view reverse {order};
+  for (auto& uid : reverse) {
+    if (component[uid] == std::numeric_limits<CT>::max()) {
+      component[uid] = cid;
+      vertices_depth_first_search_view<GT> dfs(g_t, uid);
+      for (auto&& [vid, v] : dfs) {
+        if (component[vid] != std::numeric_limits<CT>::max()) {
+          dfs.cancel(cancel_search::cancel_branch);
+        }
+        else {
+          component[vid] = cid;
+        }
+      }
+      ++cid;
+    }
+  }
+}
+
+template <adjacency_list G,
+          ranges::random_access_range Component>
+requires ranges::random_access_range<vertex_range_t<G>> && integral<vertex_id_t<G>>
+void connected_components(G&&            g,        // graph
+                          Component&     component // out: connected component assignment
+) {
+  size_t N(size(vertices(g)));
+  std::vector<bool> visited(N, false);
+  using CT = typename std::decay<decltype(*component.begin())>::type;
+  std::fill(component.begin(), component.end(), std::numeric_limits<CT>::max());
+  
+  CT cid = 0;
+  for (auto&& [uid, u] : views::vertexlist(g)) {
+    if (visited[uid]) {
+      continue;
+    }
+    visited[uid] = true;
+    component[uid] = cid;
+    vertices_depth_first_search_view<G, void> dfs(g, uid);
+    for (auto&& [vid, v] : dfs) {
+      component[vid] = cid;
+      visited[vid] = true;
+    }
+    ++cid;
+  }
+}
+
+} // namespace std::graph
+
+#endif //GRAPH_CC_HPP

tests/CMakeLists.txt

@@ -54,6 +54,7 @@ set(UNITTEST_SOURCES
     "mis_tests.cpp" 
     "mst_tests.cpp"
     "tc_tests.cpp"
+    "cc_tests.cpp"
 )
 
 foreach(SOURCE IN LISTS UNITTEST_SOURCES)

tests/cc_tests.cpp

@@ -0,0 +1,84 @@
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/catch_template_test_macros.hpp>
+#include "csv_routes.hpp"
+#include "graph/graph.hpp"
+#include "graph/algorithm/connected_components.hpp"
+#include "graph/container/dynamic_graph.hpp"
+#include "graph/views/incidence.hpp"
+#ifdef _MSC_VER
+#  include "Windows.h"
+#endif
+
+#define TEST_OPTION_OUTPUT (1) // output tests for visual inspection
+#define TEST_OPTION_GEN (2)    // generate unit test code to be pasted into this file
+#define TEST_OPTION_TEST (3)   // run unit tests
+#define TEST_OPTION TEST_OPTION_TEST
+
+using std::cout;
+using std::endl;
+
+using std::graph::vertex_t;
+using std::graph::vertex_id_t;
+using std::graph::vertex_reference_t;
+using std::graph::vertex_iterator_t;
+using std::graph::vertex_edge_range_t;
+using std::graph::edge_t;
+
+using std::graph::vertices;
+using std::graph::edges;
+using std::graph::vertex_value;
+using std::graph::target_id;
+using std::graph::target;
+using std::graph::edge_value;
+using std::graph::find_vertex;
+using std::graph::vertex_id;
+
+using routes_vol_graph_traits = std::graph::container::vol_graph_traits<double, std::string, std::string>;
+using routes_vol_graph_type   = std::graph::container::dynamic_adjacency_graph<routes_vol_graph_traits>;
+
+#if 1
+TEST_CASE("strongly connected components test", "[strong cc]") {
+  init_console();
+
+  using G  = routes_vol_graph_type;
+  auto&& g = load_ordered_graph<G>(TEST_DATA_ROOT_DIR "cc_directed.csv", name_order_policy::alphabetical);
+  G gt;
+  
+  std::vector<std::tuple<vertex_id_t<G>,vertex_id_t<G>,double>> reverse;
+  vertex_id_t<G> vid = 0;
+  for ( auto && u : vertices(g) ) {
+    for ( auto && v : edges(g, u)) {
+      reverse.push_back(std::make_tuple(target_id(g,v), vid, edge_value(g,v)));
+    }
+    ++vid;
+  }
+                             
+
+  using value = std::ranges::range_value_t<decltype(reverse)>;
+
+  vertex_id_t<G> N = size(vertices(g));
+  using edge_desc = std::graph::edge_descriptor<vertex_id_t<G>, true, void, double>;
+  auto edge_proj  = [](const value& val) -> edge_desc {
+    return edge_desc{std::get<0>(val), std::get<1>(val), std::get<2>(val)};
+  };
+
+  gt.load_edges(reverse, edge_proj, N);
+
+  std::vector<size_t> component(size(vertices(g)));
+  std::graph::kosaraju(g, gt, component);
+  
+  REQUIRE( *std::ranges::max_element( component ) == 2 );
+}
+#endif
+
+TEST_CASE("connected components test", "[cc]") {
+  init_console();
+  
+  using G  = routes_vol_graph_type;
+  auto&& g = load_ordered_graph<G>(TEST_DATA_ROOT_DIR "cc_undirected.csv", name_order_policy::alphabetical);
+
+  std::vector<size_t> component(size(vertices(g)));
+  std::graph::connected_components(g, component);
+  
+  REQUIRE( *std::ranges::max_element( component ) == 2 );
+}