From 743ce375bd9a3c5f6cba191bcfa9b50be17d9760 Mon Sep 17 00:00:00 2001
From: redpony <redpony@ec762483-ff6d-05da-a07a-a48fb63a330f>
Date: Wed, 25 Aug 2010 02:14:41 +0000
Subject: crp with explicit table tracking

git-svn-id: https://ws10smt.googlecode.com/svn/trunk@618 ec762483-ff6d-05da-a07a-a48fb63a330f
---
 gi/clda/src/ccrp.h | 139 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 gi/clda/src/ccrp.h

(limited to 'gi/clda/src/ccrp.h')

diff --git a/gi/clda/src/ccrp.h b/gi/clda/src/ccrp.h
new file mode 100644
index 00000000..e978225d
--- /dev/null
+++ b/gi/clda/src/ccrp.h
@@ -0,0 +1,139 @@
+#ifndef _CCRP_H_
+#define _CCRP_H_
+
+#include <cassert>
+#include <cmath>
+#include <list>
+#include <iostream>
+#include <vector>
+#include <tr1/unordered_map>
+#include <boost/functional/hash.hpp>
+#include "sampler.h"
+
+// Chinese restaurant process (Pitman-Yor parameters) with explicit table
+// tracking.
+
+template <typename Dish, typename DishHash = boost::hash<Dish> >
+class CCRP {
+ public:
+  CCRP(double disc, double conc) : num_tables_(), num_customers_(), discount_(disc), concentration_(conc) {}
+
+  int increment(const Dish& dish, const double& p0, MT19937* rng) {
+    DishLocations& loc = dish_locs_[dish];
+    bool share_table = false;
+    if (loc.dish_count_) {
+      const double p_empty = (concentration_ + num_tables_ * discount_) * p0;
+      const double p_share = (loc.dish_count_ - loc.table_counts_.size() * discount_);
+      share_table = rng->SelectSample(p_empty, p_share);
+    }
+    if (share_table) {
+      double r = rng->next() * (loc.dish_count_ - loc.table_counts_.size() * discount_);
+      for (typename std::list<unsigned>::iterator ti = loc.table_counts_.begin();
+           ti != loc.table_counts_.end(); ++ti) {
+        r -= (*ti - discount_);
+        if (r <= 0.0) {
+          ++(*ti);
+          break;
+        }
+      }
+      if (r > 0.0) {
+        std::cerr << "Serious error: r=" << r << std::endl;
+        Print(&std::cerr);
+        assert(r <= 0.0);
+      }
+    } else {
+      loc.table_counts_.push_back(1u);
+      ++num_tables_;
+    }
+    ++loc.dish_count_;
+    ++num_customers_;
+    return (share_table ? 0 : 1);
+  }
+
+  int decrement(const Dish& dish, MT19937* rng) {
+    DishLocations& loc = dish_locs_[dish];
+    assert(loc.dish_count_);
+    if (loc.dish_count_ == 1) {
+      dish_locs_.erase(dish);
+      --num_tables_;
+      --num_customers_;
+      return -1;
+    } else {
+      int delta = 0;
+      double r = rng->next() * (loc.dish_count_ - loc.table_counts_.size() * discount_);
+      --loc.dish_count_;
+      for (typename std::list<unsigned>::iterator ti = loc.table_counts_.begin();
+           ti != loc.table_counts_.end(); ++ti) {
+        r -= (*ti - discount_);
+        if (r <= 0.0) {
+          if ((--(*ti)) == 0) {
+            --num_tables_;
+            delta = -1;
+            loc.table_counts_.erase(ti);
+          }
+          break;
+        }
+      }
+      if (r > 0.0) {
+        std::cerr << "Serious error: r=" << r << std::endl;
+        Print(&std::cerr);
+        assert(r <= 0.0);
+      }
+      --num_customers_;
+      return delta;
+    }
+  }
+
+  double prob(const Dish& dish, const double& p0) const {
+    const typename std::tr1::unordered_map<Dish, DishLocations, DishHash>::const_iterator it = dish_locs_.find(dish);
+    const double r = num_tables_ * discount_ + concentration_;
+    if (it == dish_locs_.end()) {
+      return r * p0 / (num_customers_ + concentration_);
+    } else {
+      return (it->second.dish_count_ - discount_ * it->second.table_counts_.size() + r * p0) /
+               (num_customers_ + concentration_);
+    }
+  }
+
+  double llh() const {
+    if (num_customers_) {
+      std::cerr << "not implemented\n";
+      return 0.0;
+    } else {
+      return 0.0;
+    }
+  }
+
+  struct DishLocations {
+    DishLocations() : dish_count_() {}
+    unsigned dish_count_;
+    std::list<unsigned> table_counts_; // list<> gives O(1) deletion and insertion, which we want
+  };
+
+  void Print(std::ostream* out) const {
+    for (typename std::tr1::unordered_map<Dish, DishLocations, DishHash>::const_iterator it = dish_locs_.begin();
+         it != dish_locs_.end(); ++it) {
+      (*out) << it->first << " (" << it->second.dish_count_ << " on " << it->second.table_counts_.size() << " tables): ";
+      for (typename std::list<unsigned>::const_iterator i = it->second.table_counts_.begin();
+           i != it->second.table_counts_.end(); ++i) {
+        (*out) << " " << *i;
+      }
+      (*out) << std::endl;
+    }
+  }
+
+  unsigned num_tables_;
+  unsigned num_customers_;
+  std::tr1::unordered_map<Dish, DishLocations, DishHash> dish_locs_;
+
+  double discount_;
+  double concentration_;
+};
+
+template <typename T,typename H>
+std::ostream& operator<<(std::ostream& o, const CCRP<T,H>& c) {
+  c.Print(&o);
+  return o;
+}
+
+#endif
-- 
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