added reverse

Makefile

@@ -14,7 +14,7 @@ NABO_LIBS+=-lnabo
 
 COMMON=kgraph.o metric.o
 HEADERS=kgraph.h kgraph-data.h 
-PROGS=resave index search prune split fvec2lshkit txt2lshkit
+PROGS=resave index search prune split fvec2lshkit txt2lshkit reverse
 EXTRA_PROGS=test 
 FLANN_PROGS=flann_index flann_search
 NABO_PROGS=nabo_search

index.cpp

@@ -58,6 +58,7 @@ int main (int argc, char *argv[]) {
     ("delta", po::value(&params.delta)->default_value(default_delta), "")
     ("recall", po::value(&params.recall)->default_value(default_recall), "")
     ("prune", po::value(&params.prune)->default_value(default_prune), "")
+    ("reverse", po::value(&params.reverse)->default_value(default_reverse), "")
     ("noise", po::value(&noise)->default_value(0), "noise")
     ("seed", po::value(&params.seed)->default_value(default_seed), "")
     ("dim,D", po::value(&D), "dimension, see format")

kgraph.cpp

@@ -61,6 +61,10 @@ namespace kgraph {
         return n1.dist < n2.dist;
     }
 
+    static inline bool operator == (Neighbor const &n1, Neighbor const &n2) {
+        return n1.id == n2.id;
+    }
+
     typedef vector<Neighbor> Neighbors;
 
     // both pool and knn should be sorted in ascending order
@@ -241,6 +245,46 @@ namespace kgraph {
         vector<vector<Neighbor>> graph;
         bool no_dist;   // Distance & flag information in Neighbor is not valid.
 
+        void reverse (int rev_k) {
+            if (rev_k == 0) return;
+            if (no_dist) throw runtime_error("Need distance information to reverse graph");
+            vector<vector<Neighbor>> ng; // new graph adds on original one
+            {
+                cerr << "Graph completion with reverse edges..." << endl;
+                ng = graph;
+                progress_display progress(graph.size(), cerr);
+                for (unsigned i = 0; i < graph.size(); ++i) {
+                    auto const &v = graph[i];
+                    unsigned K = M[i];
+                    if (rev_k > 0) {
+                        K = rev_k;
+                        if (K > v.size()) K = v.size();
+                    }
+                    //if (v.size() < XX) XX = v.size();
+                    for (unsigned j = 0; j < K; ++j) {
+                        auto const &e = v[j];
+                        auto re = e;
+                        re.id = i;
+                        ng[e.id].push_back(re);
+                    }
+                    ++progress;
+                }
+                graph.swap(ng);
+            }
+            {
+                cerr << "Reranking edges..." << endl;
+                progress_display progress(graph.size(), cerr);
+#pragma omp parallel for
+                for (unsigned i = 0; i < graph.size(); ++i) {
+                    auto &v = graph[i];
+                    std::sort(v.begin(), v.end());
+                    v.resize(std::unique(v.begin(), v.end()) - v.begin());
+                    M[i] = v.size();
+#pragma omp critical
+                    ++progress;
+                }
+            }
+        }
     public:
         virtual ~KGraphImpl () {
         }
@@ -523,6 +567,7 @@ namespace kgraph {
             }
         }
 
+
         void prune2 () {
             vector<vector<unsigned>> reverse(graph.size()); // reverse of new graph
             vector<unsigned> new_L(graph.size(), 0);
@@ -875,6 +920,9 @@ namespace kgraph {
                     knn[k].dist = pool[k].dist;
                 }
             }
+            if (params.reverse) {
+                reverse(params.reverse);
+            }
             if (params.prune) {
                 prune(o, params.prune);
             }

kgraph.h

@@ -27,7 +27,12 @@ namespace kgraph {
         PRUNE_LEVEL_1 = 1,
         PRUNE_LEVEL_2 = 2
     };
+    enum {
+        REVERSE_AUTO = -1,
+        REVERSE_NONE = 0,
+    };
     static unsigned const default_prune = 0;
+    static int const default_reverse = REVERSE_NONE;
 
     /// Verbosity control
     /** Set verbosity = 0 to disable information output to stderr.
@@ -95,9 +100,10 @@ namespace kgraph {
             float delta;
             float recall;
             unsigned prune;
+            int reverse;
 
             /// Construct with default values.
-            IndexParams (): iterations(default_iterations), L(default_L), K(default_K), S(default_S), R(default_R), controls(default_controls), seed(default_seed), delta(default_delta), recall(default_recall), prune(default_prune) {
+            IndexParams (): iterations(default_iterations), L(default_L), K(default_K), S(default_S), R(default_R), controls(default_controls), seed(default_seed), delta(default_delta), recall(default_recall), prune(default_prune), reverse(default_reverse) {
             }
         };
 

version

@@ -1 +1 @@
-1.4
+1.5