AENC/switchchain Changeset - 7bef7b203f4e · Centrum Wiskunde & Informatica (CWI)

Changeset - 7bef7b203f4e

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Tom Bannink - 9 years ago 2017-01-27 12:48:48
tom.bannink@cwi.nl

Add test with an n=6 graph

1 file changed with 50 insertions and 15 deletions:

cpp/switchchain.cpp

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cpp/switchchain.cpp

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 #include <algorithm>
 #include <iostream>
 #include <numeric>
 #include <random>
@@ @@ -32,22 +33,30 @@ typedef std::vector<DiDegree> DiDegreeSequence; @@
 class Graph {
   public:
-    Graph() : edgeCount(0) {}
     Graph() {}
-    Graph(int n) : edgeCount(0) { adj.resize(n); }
     Graph(int n) { adj.resize(n); }
     ~Graph() {}
     bool createFromSequence(const DegreeSequence &d) {
         edgeCount = std::accumulate(d.begin(), d.end(), 0);
     bool createFromDegreeSequence(const DegreeSequence &d) {
         //
         // TODO
         //
         // See
         // http://stackoverflow.com/questions/13102738/creating-graphs-using-a-degree-sequence
         // See https://en.wikipedia.org/wiki/Havel%E2%80%93Hakimi_algorithm
         (void)d;
         return false;
+    }
     DegreeSequence getDegreeSequence() const {
         DegreeSequence d(adj.size());
         std::transform(adj.begin(), adj.end(), d.begin(),
                        [](const auto &u) { return u.size(); });
         return d;
+    }
     bool hasEdge(const Edge &e) const {
         for (int v : adj[e.u]) {
             if (v == e.v)
@@ @@ -56,6 +65,15 @@ class Graph { @@
         return false;
+    }
     bool addEdge(const Edge &e) {
         if (hasEdge(e))
             return false;
         edges.push_back(e);
         adj[e.u].push_back(e.v);
         adj[e.v].push_back(e.u);
         return true;
+    }
     // There are two possible edge exchanges
     // switchType indicates which one is desired
     // Returns false if the switch is not possible
@@ @@ -132,23 +150,31 @@ class Graph { @@
     // The two should be kept consistent at all times
     std::vector<std::vector<int>> adj;
     std::vector<Edge> edges;
     int edgeCount;
 };
 class SwitchChain {
   public:
     SwitchChain() : permutationDistribution(0, 2) {
+    SwitchChain() : mt(std::random_device{}()), permutationDistribution(0, 2) {
         // random_device uses hardware entropy if available
         std::random_device rd;
         mt.seed(rd());
         // std::random_device rd;
         // mt.seed(rd());
+    }
     ~SwitchChain() {}
     bool initialize(const DegreeSequence &d) {
-        if (!g.createFromSequence(d))
+        if (!g.createFromDegreeSequence(d))
             return false;
         edgeDistribution.param(
             std::uniform_int_distribution<>::param_type(0, g.edgeCount - 1));
             std::uniform_int_distribution<>::param_type(0, g.edges.size() - 1));
         return true;
+    }
     bool initialize(const Graph &gstart) {
         if (gstart.edges.size() == 0)
             return false;
         g = gstart;
         edgeDistribution.param(
             std::uniform_int_distribution<>::param_type(0, g.edges.size() - 1));
         return true;
+    }
@@ @@ -188,19 +214,28 @@ class SwitchChain { @@
 };
 int main() {
     Graph g(6);
     g.addEdge({0, 1});
     g.addEdge({0, 2});
     g.addEdge({0, 3});
     g.addEdge({2, 3});
     g.addEdge({3, 4});
     g.addEdge({3, 5});
     SwitchChain chain;
-    if (!chain.initialize({3, 2, 4, 2, 2, 1})) {
+    if (!chain.initialize(g)) {
         std::cerr << "Could not initialize Markov chain.\n";
         return 1;
+    }
     std::cout << "Starting switch Markov chain" << std::endl;
     int movesDone = 0;
     for (int i = 0; i < 100; ++i)
     int movesTotal = 10000;
     for (int i = 0; i < movesTotal; ++i)
         if (chain.doMove())
             ++movesDone;
-    std::cout << movesDone << "/100 moves succeeded." << std::endl;
+    std::cout << movesDone << '/' << movesTotal << " moves succeeded." << std::endl;
     return 0;
+}

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