explain the sparsity ratio

paddle/parameter/ParameterUpdaterHook.cpp

@@ -61,7 +61,7 @@ public:
     maskTemp_ = Vector::create(para->getSize(), false);
     maskTemp_->zeroMem();
     real* dataPtr = maskTemp_->getData();
-    size_t sparsityNum = para->getSize() * (1 - sparsityRatio_);
+    size_t nonZeroNum = para->getSize() * (1 - sparsityRatio_);
 
     VectorPtr vecCpu = Vector::create(para->getSize(), false);
     vecCpu->copyFrom(*vec);
@@ -71,10 +71,10 @@ public:
       param.push_back(std::make_pair(fabs(vecCpu->getData()[i]), i));
 
     std::partial_sort(param.begin(),
-                      param.begin() + sparsityNum,
+                      param.begin() + nonZeroNum,
                       param.end(),
                       sortPairAscend);
-    for (size_t i = 0; i < sparsityNum; i++) dataPtr[param[i].second] = 1.0;
+    for (size_t i = 0; i < nonZeroNum; i++) dataPtr[param[i].second] = 1.0;
 
     // Currently just use a mask vector for hack.
     if (para->useGpu()) {

proto/ParameterConfig.proto

@@ -27,7 +27,8 @@ enum ParameterInitStrategy {
 message ParameterUpdaterHookConfig {
   // hook type such as  'pruning'
   required string type = 1;
-  optional double sparsity_ratio = 2 [default = 0.8];
+  // this represents the ratio of zero element to be set by the Parameter 
+  optional double sparsity_ratio = 2 [default = 0.6];
 }
 
 message ParameterConfig {

python/paddle/trainer_config_helpers/attrs.py

@@ -65,7 +65,8 @@ class HookAttribute(object):
     :param  type: Hook type, eg: 'pruning'
     :type type: string
 
-    :param sparsity_ratio: Must be specified if hook type is 'pruning'
+    :param sparsity_ratio: Must be specified if hook type is 'pruning', 
+                           it represents the ratio of the zero elements to be set by the Parameter.
     :type sparsity_ratio: float or None
 	
     """