simple sparse vector type

1 files changed, 116 insertions, 0 deletions

diff --git a/fast/sparse_vector.hh b/fast/sparse_vector.hh
new file mode 100644
index 0000000..8fdc1b9
--- /dev/null
+++ b/fast/sparse_vector.hh
@@ -0,0 +1,116 @@
+#pragma once
+
+#include <unordered_map>
+#include <vector>
+#include <sstream>
+
+#include "hypergraph.hh" // FIXME
+
+using namespace std;
+
+
+namespace Sv {
+
+template<typename K, typename V>
+struct SparseVector {
+  unordered_map<K, V> m_;
+  V zero = 0.0;
+
+  void
+  insert(K k, V v) { m_[k] = v; };
+
+  weight_t 
+  dot(SparseVector& other)
+  {
+  };
+
+  V&
+  operator[](const K& k)
+  {
+    return at(k);
+  };
+
+  const V&
+  at(const K& k) const
+  {
+     if (m_.find(k) == m_.end())
+      return zero;
+    else
+      return m_.at(k);
+  }
+
+  SparseVector
+  operator+(const SparseVector& other) const
+  {
+    SparseVector<K,V> v;
+    v.m_.insert(m_.begin(), m_.end());
+    v.m_.insert(other.m_.begin(), other.m_.end());
+    for (auto it = v.m_.begin(); it != v.m_.end(); it++)
+      v.m_[it->first] = this->at(it->first) + other.at(it->first);
+    return v;
+  };
+
+  SparseVector&
+  operator+=(const SparseVector& other)
+  {
+    for (auto it = other.m_.begin(); it != other.m_.end(); it++)
+      m_[it->first] += it->second;
+    return *this;
+  };
+
+  SparseVector
+  operator-(const SparseVector& other) const
+  {
+    SparseVector<K,V> v;
+    v.m_.insert(m_.begin(), m_.end());
+    v.m_.insert(other.m_.begin(), other.m_.end());
+    for (auto it = v.m_.begin(); it != v.m_.end(); it++)
+      v.m_[it->first] = this->at(it->first) - other.at(it->first);
+    return v;
+  };
+
+  SparseVector&
+  operator-=(const SparseVector& other)
+  {
+    for (auto it = other.m_.begin(); it != other.m_.end(); it++)
+      m_[it->first] -= it->second;
+    return *this;
+  };
+
+  SparseVector
+  operator*(V f) const
+  {
+    SparseVector<K,V> v;
+    for (auto it = m_.begin(); it != m_.end(); it++)
+      v.m_[it->first] = this->at(it->first) * f;
+    return v;
+  };
+
+  SparseVector&
+  operator*=(V f)
+  {
+    for (auto it = m_.begin(); it != m_.end(); it++)
+      m_[it->first] *= f;
+    return *this;
+  };
+
+  string
+  repr() const
+  {
+    ostringstream os; 
+    os << "SparseVector<{";
+    for (auto it = m_.begin(); it != m_.end(); it ++) {
+      os << "'" << it->first << "'=" << it->second;
+      if (next(it) != m_.end())
+        os << ", ";
+    }
+    os << "}>";
+    return os.str();
+  };
+
+  friend ostream&
+  operator<<(ostream& os, const SparseVector& v) { return os << v.repr(); }
+};
+
+} // namespace
+