Simplify the top-k argmax layer using std::sort

1 files changed, 8 insertions, 30 deletions

diff --git a/src/caffe/layers/argmax_layer.cpp b/src/caffe/layers/argmax_layer.cpp
index 1fe2a89e..00c17f1c 100644
--- a/src/caffe/layers/argmax_layer.cpp
+++ b/src/caffe/layers/argmax_layer.cpp
@@ -1,5 +1,6 @@
 // Copyright 2014 BVLC and contributors.
 
+#include <algorithm>
 #include <cfloat>
 #include <queue>
 #include <vector>
@@ -28,50 +29,27 @@ void ArgMaxLayer<Dtype>::SetUp(const vector<Blob<Dtype>*>& bottom,
 }
 
 template <typename Dtype>
-class IDAndValueComparator {
- public:
-  bool operator() (const std::pair<size_t, Dtype>& lhs,
-                   const std::pair<size_t, Dtype>& rhs) const {
-    return lhs.second < rhs.second || (lhs.second == rhs.second &&
-        lhs.first < rhs.first);
-  }
-};
-
-template <typename Dtype>
 Dtype ArgMaxLayer<Dtype>::Forward_cpu(const vector<Blob<Dtype>*>& bottom,
     vector<Blob<Dtype>*>* top) {
   const Dtype* bottom_data = bottom[0]->cpu_data();
   Dtype* top_data = (*top)[0]->mutable_cpu_data();
   int num = bottom[0]->num();
   int dim = bottom[0]->count() / bottom[0]->num();
-  Dtype value;
   for (int i = 0; i < num; ++i) {
-    std::priority_queue<std::pair<size_t, Dtype>,
-        std::vector<std::pair<size_t, Dtype> >, IDAndValueComparator<Dtype> >
-        top_k_results;
+    std::vector<std::pair<int, Dtype> > bottom_data_vector;
     for (int j = 0; j < dim; ++j) {
-      value = -(bottom_data[i * dim + j]);
-      if (top_k_results.size() >= top_k_) {
-        if (value < top_k_results.top().second) {
-          top_k_results.pop();
-          top_k_results.push(std::make_pair(j, value));
-        }
-      } else {
-        top_k_results.push(std::make_pair(j, value));
-      }
+      bottom_data_vector.push_back(std::make_pair(j, bottom_data[i * dim + j]));
     }
+    std::sort(bottom_data_vector.begin(), bottom_data_vector.end(),
+              int_Dtype_pair_greater<Dtype>);
     if (out_max_val_) {
       for (int j = 0; j < top_k_; ++j) {
-        top_data[i * 2 * top_k_ + (top_k_ - 1 - j) * 2] =
-            top_k_results.top().first;
-        top_data[i * 2 * top_k_ + (top_k_ - 1 - j) * 2 + 1] =
-            -(top_k_results.top().second);
-        top_k_results.pop();
+        top_data[(*top)[0]->offset(i, 0, j)] = bottom_data_vector[j].first;
+        top_data[(*top)[0]->offset(i, 1, j)] = bottom_data_vector[j].second;
       }
     } else {
       for (int j = 0; j < top_k_; ++j) {
-        top_data[i * top_k_ + (top_k_ - 1 - j)] = top_k_results.top().first;
-        top_k_results.pop();
+        top_data[(*top)[0]->offset(i, 0, j)] = bottom_data_vector[j].first;
       }
     }
   }