From b6c44f82ffca74cc38cf6039ac9ab3c2c66fd5d6 Mon Sep 17 00:00:00 2001
From: Chris Dyer <cdyer@allegro.clab.cs.cmu.edu>
Date: Mon, 25 Nov 2013 01:03:58 -0500
Subject: l1 version of adagrad optimizer

---
 training/crf/mpi_adagrad_optimize.cc | 43 ++++++++++++++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 2 deletions(-)

(limited to 'training/crf')

diff --git a/training/crf/mpi_adagrad_optimize.cc b/training/crf/mpi_adagrad_optimize.cc
index 05e7c35f..af963e3a 100644
--- a/training/crf/mpi_adagrad_optimize.cc
+++ b/training/crf/mpi_adagrad_optimize.cc
@@ -194,7 +194,7 @@ class AdaGradOptimizer {
     for (auto& gi : g) {
 #else
     for (SparseVector<double>::const_iterator it = g.begin(); it != g.end(); ++it) {
-      const pair<unsigne,double>& gi = *it;
+      const pair<unsigned,double>& gi = *it;
 #endif
       if (gi.second) {
         G[gi.first] += gi.second * gi.second;
@@ -206,6 +206,44 @@ class AdaGradOptimizer {
   vector<double> G;
 };
 
+class AdaGradL1Optimizer {
+ public:
+  explicit AdaGradL1Optimizer(double e, double l) :
+      t(),
+      eta(e),
+      lambda(l),
+      G() {}
+  void update(const SparseVector<double>& g, vector<double>* x) {
+    t += 1.0;
+    if (x->size() > G.size()) {
+      G.resize(x->size(), 0.0);
+      u.resize(x->size(), 0.0);
+    }
+#if HAVE_CXX11
+    for (auto& gi : g) {
+#else
+    for (SparseVector<double>::const_iterator it = g.begin(); it != g.end(); ++it) {
+      const pair<unsigned,double>& gi = *it;
+#endif
+      if (gi.second) {
+        u[gi.first] += gi.second;
+        G[gi.first] += gi.second * gi.second;
+        double z = fabs(u[gi.first] / t) - lambda;
+        double s = 1;
+        if (u[gi.first] > 0) s = -1;
+        if (z > 0 && G[gi.first])
+          (*x)[gi.first] = eta * s * z * t / sqrt(G[gi.first]);
+        else
+          (*x)[gi.first] = 0.0;
+      }
+    }
+  }
+  double t;
+  const double eta;
+  const double lambda;
+  vector<double> G, u;
+};
+
 unsigned non_zeros(const vector<double>& x) {
   unsigned nz = 0;
   for (unsigned i = 0; i < x.size(); ++i)
@@ -286,7 +324,8 @@ int main(int argc, char** argv) {
     init_weights.clear();
   }
 
-  AdaGradOptimizer adagrad(conf["eta"].as<double>());
+  //AdaGradOptimizer adagrad(conf["eta"].as<double>());
+  AdaGradL1Optimizer adagrad(conf["eta"].as<double>(), conf["regularization_strength"].as<double>());
   int iter = -1;
   bool converged = false;
 
-- 
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