use template parameter inference to figure out what type to use for probability computations, templatatize number of floors in MFCR rather than compile-time set

1 files changed, 36 insertions, 32 deletions

diff --git a/utils/mfcr.h b/utils/mfcr.h
index aeaf599d..6cc0ebf1 100644
--- a/utils/mfcr.h
+++ b/utils/mfcr.h
@@ -8,6 +8,7 @@
 #include <list>
 #include <iostream>
 #include <vector>
+#include <iterator>
 #include <tr1/unordered_map>
 #include <boost/functional/hash.hpp>
 #include "sampler.h"
@@ -35,12 +36,11 @@ std::ostream& operator<<(std::ostream& o, const TableCount& tc) {
 // referenced therein.
 // http://www.aclweb.org/anthology/P/P09/P09-2085.pdf
 //
-template <typename Dish, typename DishHash = boost::hash<Dish> >
+template <unsigned Floors, typename Dish, typename DishHash = boost::hash<Dish> >
 class MFCR {
  public:
 
-  MFCR(unsigned num_floors, double d, double strength) :
-    num_floors_(num_floors),
+  MFCR(double d, double strength) :
     num_tables_(),
     num_customers_(),
     discount_(d),
@@ -50,8 +50,7 @@ class MFCR {
     strength_prior_shape_(std::numeric_limits<double>::quiet_NaN()),
     strength_prior_rate_(std::numeric_limits<double>::quiet_NaN()) {}
 
-  MFCR(unsigned num_floors, double discount_strength, double discount_beta, double strength_shape, double strength_rate, double d = 0.9, double strength = 10.0) :
-    num_floors_(num_floors),
+  MFCR(double discount_strength, double discount_beta, double strength_shape, double strength_rate, double d = 0.9, double strength = 10.0) :
     num_tables_(),
     num_customers_(),
     discount_(d),
@@ -111,22 +110,22 @@ class MFCR {
   }
 
   // returns (delta, floor) indicating whether a new table (delta) was opened and on which floor
-  TableCount increment(const Dish& dish, const std::vector<double>& p0s, const std::vector<double>& lambdas, MT19937* rng) {
-    assert(p0s.size() == num_floors_);
-    assert(lambdas.size() == num_floors_);
-
+  template <class InputIterator, class InputIterator2>
+  TableCount increment(const Dish& dish, InputIterator p0s, InputIterator2 lambdas, MT19937* rng) {
     DishLocations& loc = dish_locs_[dish];
     // marg_p0 = marginal probability of opening a new table on any floor with label dish
-    const double marg_p0 = std::inner_product(p0s.begin(), p0s.end(), lambdas.begin(), 0.0);
-    assert(marg_p0 <= 1.0);
+    typedef typename std::iterator_traits<InputIterator>::value_type F;
+    const F marg_p0 = std::inner_product(p0s, p0s + Floors, lambdas, F(0.0));
+    assert(marg_p0 <= F(1.0001));
     int floor = -1;
     bool share_table = false;
     if (loc.total_dish_count_) {
-      const double p_empty = (strength_ + num_tables_ * discount_) * marg_p0;
-      const double p_share = (loc.total_dish_count_ - loc.table_counts_.size() * discount_);
+      const F p_empty = F(strength_ + num_tables_ * discount_) * marg_p0;
+      const F p_share = F(loc.total_dish_count_ - loc.table_counts_.size() * discount_);
       share_table = rng->SelectSample(p_empty, p_share);
     }
     if (share_table) {
+      // this can be done with doubles since P0 (which may be tiny) is not involved
       double r = rng->next() * (loc.total_dish_count_ - loc.table_counts_.size() * discount_);
       for (typename std::list<TableCount>::iterator ti = loc.table_counts_.begin();
            ti != loc.table_counts_.end(); ++ti) {
@@ -143,12 +142,18 @@ class MFCR {
         assert(r <= 0.0);
       }
     } else { // sit at currently empty table -- must sample what floor
-      double r = rng->next() * marg_p0;
-      for (unsigned i = 0; i < p0s.size(); ++i) {
-        r -= p0s[i] * lambdas[i];
-        if (r <= 0.0) {
-          floor = i;
-          break;
+      if (Floors == 1) {
+        floor = 0;
+      } else {
+        F r = F(rng->next()) * marg_p0;
+        for (unsigned i = 0; i < Floors; ++i) {
+          r -= (*p0s) * (*lambdas);
+          ++p0s;
+          ++lambdas;
+          if (r <= F(0.0)) {
+            floor = i;
+            break;
+          }
         }
       }
       assert(floor >= 0);
@@ -200,18 +205,18 @@ class MFCR {
     return TableCount(delta, floor);
   }
 
-  double prob(const Dish& dish, const std::vector<double>& p0s, const std::vector<double>& lambdas) const {
-    assert(p0s.size() == num_floors_);
-    assert(lambdas.size() == num_floors_);
-    const double marg_p0 = std::inner_product(p0s.begin(), p0s.end(), lambdas.begin(), 0.0);
-    assert(marg_p0 <= 1.0);
+  template <class InputIterator, class InputIterator2>
+  typename std::iterator_traits<InputIterator>::value_type prob(const Dish& dish, InputIterator p0s, InputIterator2 lambdas) const {
+    typedef typename std::iterator_traits<InputIterator>::value_type F;
+    const F marg_p0 = std::inner_product(p0s, p0s + Floors, lambdas, F(0.0));
+    assert(marg_p0 <= F(1.0001));
     const typename std::tr1::unordered_map<Dish, DishLocations, DishHash>::const_iterator it = dish_locs_.find(dish);
-    const double r = num_tables_ * discount_ + strength_;
+    const F r = F(num_tables_ * discount_ + strength_);
     if (it == dish_locs_.end()) {
-      return r * marg_p0 / (num_customers_ + strength_);
+      return r * marg_p0 / F(num_customers_ + strength_);
     } else {
-      return (it->second.total_dish_count_ - discount_ * it->second.table_counts_.size() + r * marg_p0) /
-               (num_customers_ + strength_);
+      return (F(it->second.total_dish_count_ - discount_ * it->second.table_counts_.size()) + F(r * marg_p0)) /
+               F(num_customers_ + strength_);
     }
   }
 
@@ -303,7 +308,7 @@ class MFCR {
   };
 
   void Print(std::ostream* out) const {
-    (*out) << "MFCR(d=" << discount_ << ",strength=" << strength_ << ") customers=" << num_customers_ << std::endl;
+    (*out) << "MFCR<" << Floors << ">(d=" << discount_ << ",strength=" << strength_ << ") customers=" << num_customers_ << std::endl;
     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.total_dish_count_ << " on " << it->second.table_counts_.size() << " tables): ";
@@ -323,7 +328,6 @@ class MFCR {
     return dish_locs_.end();
   }
 
-  unsigned num_floors_;
   unsigned num_tables_;
   unsigned num_customers_;
   std::tr1::unordered_map<Dish, DishLocations, DishHash> dish_locs_;
@@ -340,8 +344,8 @@ class MFCR {
   double strength_prior_rate_;
 };
 
-template <typename T,typename H>
-std::ostream& operator<<(std::ostream& o, const MFCR<T,H>& c) {
+template <unsigned N,typename T,typename H>
+std::ostream& operator<<(std::ostream& o, const MFCR<N,T,H>& c) {
   c.Print(&o);
   return o;
 }