1 files changed, 101 insertions, 0 deletions
diff --git a/vest/line_optimizer.cc b/vest/line_optimizer.cc
new file mode 100644
index 00000000..98dcec34
--- /dev/null
+++ b/vest/line_optimizer.cc
@@ -0,0 +1,101 @@
+#include "line_optimizer.h"
+
+#include <limits>
+#include <algorithm>
+
+#include "sparse_vector.h"
+#include "scorer.h"
+
+using namespace std;
+
+typedef ErrorSurface::const_iterator ErrorIter;
+
+// sort by increasing x-ints
+struct IntervalComp {
+  bool operator() (const ErrorIter& a, const ErrorIter& b) const {
+    return a->x < b->x;
+  }
+};	
+
+double LineOptimizer::LineOptimize(
+  const vector<ErrorSurface>& surfaces,
+  const LineOptimizer::ScoreType type,
+  float* best_score,
+  const double epsilon) {
+  vector<ErrorIter> all_ints;
+  for (vector<ErrorSurface>::const_iterator i = surfaces.begin();
+       i != surfaces.end(); ++i) {
+    const ErrorSurface& surface = *i;
+    for (ErrorIter j = surface.begin(); j != surface.end(); ++j)
+      all_ints.push_back(j);
+  }
+  sort(all_ints.begin(), all_ints.end(), IntervalComp());
+  double last_boundary = all_ints.front()->x;
+  Score* acc = all_ints.front()->delta->GetZero();
+  float& cur_best_score = *best_score;
+  cur_best_score = (type == MAXIMIZE_SCORE ?
+    -numeric_limits<float>::max() : numeric_limits<float>::max());
+  bool left_edge = true;
+  double pos = numeric_limits<double>::quiet_NaN();
+  for (vector<ErrorIter>::iterator i = all_ints.begin();
+       i != all_ints.end(); ++i) {
+    const ErrorSegment& seg = **i;
+    assert(seg.delta);
+    if (seg.x - last_boundary > epsilon) {
+      float sco = acc->ComputeScore();
+      if ((type == MAXIMIZE_SCORE && sco > cur_best_score) ||
+          (type == MINIMIZE_SCORE && sco < cur_best_score) ) {
+        cur_best_score = sco;
+	if (left_edge) {
+	  pos = seg.x - 0.1;
+	  left_edge = false;
+	} else {
+	  pos = last_boundary + (seg.x - last_boundary) / 2;
+	}
+	// cerr << "NEW BEST: " << pos << "  (score=" << cur_best_score << ")\n";
+      }
+      // cerr << "---- s=" << sco << "\n";
+      last_boundary = seg.x;
+    }
+    // cerr << "x-boundary=" << seg.x << "\n";
+    acc->PlusEquals(*seg.delta);
+  }
+  float sco = acc->ComputeScore();
+  if ((type == MAXIMIZE_SCORE && sco > cur_best_score) ||
+      (type == MINIMIZE_SCORE && sco < cur_best_score) ) {
+    cur_best_score = sco;
+    if (left_edge) {
+      pos = 0;
+    } else {
+      pos = last_boundary + 1000.0;
+    }
+  }
+  delete acc;
+  return pos;
+}
+
+void LineOptimizer::RandomUnitVector(const vector<int>& features_to_optimize,
+                                     SparseVector<double>* axis,
+                                     RandomNumberGenerator<boost::mt19937>* rng) {
+  axis->clear();
+  for (int i = 0; i < features_to_optimize.size(); ++i)
+    axis->set_value(features_to_optimize[i], rng->next() - 0.5);
+  (*axis) /= axis->l2norm();
+}
+
+void LineOptimizer::CreateOptimizationDirections(
+     const vector<int>& features_to_optimize,
+     int additional_random_directions,
+     RandomNumberGenerator<boost::mt19937>* rng,
+     vector<SparseVector<double> >* dirs) {
+  const int num_directions = features_to_optimize.size() + additional_random_directions;
+  dirs->resize(num_directions);
+  for (int i = 0; i < num_directions; ++i) {
+    SparseVector<double>& axis = (*dirs)[i];
+    if (i < features_to_optimize.size())
+      axis.set_value(features_to_optimize[i], 1.0);
+    else
+      RandomUnitVector(features_to_optimize, &axis, rng);
+  }
+  cerr << "Generated " << num_directions << " total axes to optimize along.\n";
+}