kbest repo

1 files changed, 37 insertions, 0 deletions

diff --git a/training/kbest_repository.cc b/training/kbest_repository.cc
new file mode 100644
index 00000000..145b40a2
--- /dev/null
+++ b/training/kbest_repository.cc
@@ -0,0 +1,37 @@
+#include "kbest_repository.h"
+
+#include <boost/functional/hash.hpp>
+
+using namespace std;
+
+struct ApproxVectorHasher {
+  static const size_t MASK = 0xFFFFFFFFull;
+  union UType {
+    double f;   // leave as double
+    size_t i;
+  };
+  static inline double round(const double x) {
+    UType t;
+    t.f = x;
+    size_t r = t.i & MASK;
+    if ((r << 1) > MASK)
+      t.i += MASK - r + 1;
+    else
+      t.i &= (1ull - MASK);
+    return t.f;
+  }
+  size_t operator()(const SparseVector<double>& x) const {
+    size_t h = 0x573915839;
+    for (SparseVector<double>::const_iterator it = x.begin(); it != x.end(); ++it) {
+      UType t;
+      t.f = it->second;
+      if (t.f) {
+        size_t z = (t.i >> 32);
+        boost::hash_combine(h, it->first);
+        boost::hash_combine(h, z);
+      }
+    }
+    return h;
+  }
+};
+