1 files changed, 186 insertions, 0 deletions
diff --git a/src/sparse_vector.hh b/src/sparse_vector.hh
new file mode 100644
index 0000000..7fff338
--- /dev/null
+++ b/src/sparse_vector.hh
@@ -0,0 +1,186 @@
+#pragma once
+
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "util.hh"
+#include "types.hh"
+
+using namespace std;
+
+
+namespace Sv {
+
+template<typename K, typename V>
+struct SparseVector {
+  unordered_map<K,V> m_;
+                   V zero = 0.f;
+
+  SparseVector() {};
+
+  SparseVector(string& s)
+  {
+    from_s(this, s);
+  };
+
+  void
+  insert(K k, V v) { m_[k] = v; };
+
+  V
+  dot(SparseVector& other)
+  {
+    V r;
+    unordered_map<K,V>* o = &m_;
+    auto b = m_.cbegin();
+    auto e = m_.cend();
+    if (other.size() < size()) {
+      b = other.m_.cbegin();
+      e = other.m_.cend();
+      o = &other.m_;
+    }
+    for (auto it = b; it != e; it++)
+      r += it->second * o->at(it->first);
+
+    return r;
+  };
+
+  size_t
+  size()
+  {
+    return m_.size();
+  }
+
+  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_.cbegin(), m_.cend());
+    v.m_.insert(other.m_.cbegin(), other.m_.cend());
+    for (const auto it: v.m_)
+      v.m_[it.first] = this->at(it.first) + other.at(it.first);
+
+    return v;
+  };
+
+  SparseVector&
+  operator+=(const SparseVector& other)
+  {
+    for (const auto it: other.m_)
+      m_[it.first] += it.second;
+
+    return *this;
+  };
+
+  SparseVector
+  operator-(const SparseVector& other) const
+  {
+    SparseVector<K,V> v;
+    v.m_.insert(m_.cbegin(), m_.cend());
+    v.m_.insert(other.m_.cbegin(), other.m_.cend());
+    for (const auto it: v.m_)
+      v.m_[it.first] = this->at(it.first) - other.at(it.first);
+
+    return v;
+  };
+
+  SparseVector&
+  operator-=(const SparseVector& other)
+  {
+    for (const auto it: other.m_)
+      m_[it.first] -= it.second;
+
+    return *this;
+  };
+
+  SparseVector
+  operator*(V f) const
+  {
+    SparseVector<K,V> v;
+    for (const auto it: m_)
+      v.m_[it.first] = this->at(it.first) * f;
+
+    return v;
+  };
+
+  SparseVector&
+  operator*=(V f)
+  {
+    for (const auto it: m_)
+      m_[it.first] *= f;
+
+    return *this;
+  };
+
+  static void
+  from_s(SparseVector* w, const string& s)
+  {
+    stringstream ss(s);
+    while (!ss.eof()) {
+      string t;
+      ss >> t;
+      size_t eq = t.find_first_of("=");
+      if (eq == string::npos) {
+        return;
+      }
+      t.replace(eq, 1, " ");
+      stringstream tt(t);
+      K k; V v;
+      tt >> k >> v;
+      w->m_.emplace(k.substr(k.find_first_of("\"")+1, k.find_last_of("\"")-1), v);
+    }
+  }
+
+  ostream&
+  repr(ostream& os) const
+  {
+    os << "SparseVector<{";
+    for (auto it = m_.cbegin(); it != m_.cend(); it++) {
+      os << "'" << it->first << "'=" << it->second;
+      if (next(it) != m_.end())
+        os << ", ";
+    }
+    os << "}>";
+
+    return os;
+  };
+
+  ostream&
+  escaped(ostream& os, bool quote_keys=false) const {
+    for (auto it = m_.cbegin(); it != m_.cend(); it++) {
+      if (quote_keys) os << '"';
+      os << util::json_escape(it->first);
+      if (quote_keys) os << '"';
+      os << "=" << it->second;
+      if (next(it) != m_.cend()) os << " ";
+    }
+
+    return os;
+  };
+
+  friend ostream&
+  operator<<(ostream& os, const SparseVector& v)
+  {
+    return v.repr(os);
+  }
+};
+
+} // namespace
+