From 121348c0d795403a9c152af6f55b83dddfcf6b2e Mon Sep 17 00:00:00 2001
From: kalenhaha <chenkl198812@gmail.com>
Date: Wed, 14 May 2014 23:13:27 +0800
Subject: [PATCH] add in grad and hess rescale in lambdarank

---
 demo/rank/toy.eval              |  5 -----
 demo/rank/toy.eval.group        |  2 --
 demo/rank/toy.test              |  5 -----
 demo/rank/toy.test.group        |  2 --
 demo/rank/toy.train             | 11 -----------
 demo/rank/toy.train.group       |  2 --
 regrank/xgboost_regrank_obj.hpp | 17 ++++++++++++++---
 7 files changed, 14 insertions(+), 30 deletions(-)
 delete mode 100644 demo/rank/toy.eval
 delete mode 100644 demo/rank/toy.eval.group
 delete mode 100644 demo/rank/toy.test
 delete mode 100644 demo/rank/toy.test.group
 delete mode 100644 demo/rank/toy.train
 delete mode 100644 demo/rank/toy.train.group

diff --git a/demo/rank/toy.eval b/demo/rank/toy.eval
deleted file mode 100644
index 8dad91eb1..000000000
--- a/demo/rank/toy.eval
+++ /dev/null
@@ -1,5 +0,0 @@
-1 0:2 1:3 2:2
-0 0:2 1:3 2:2
-0 0:2 1:3 2:2
-0 0:2 1:3 2:2
-1 0:2 1:3 2:2
diff --git a/demo/rank/toy.eval.group b/demo/rank/toy.eval.group
deleted file mode 100644
index 4792e70f3..000000000
--- a/demo/rank/toy.eval.group
+++ /dev/null
@@ -1,2 +0,0 @@
-2
-3
diff --git a/demo/rank/toy.test b/demo/rank/toy.test
deleted file mode 100644
index 8dad91eb1..000000000
--- a/demo/rank/toy.test
+++ /dev/null
@@ -1,5 +0,0 @@
-1 0:2 1:3 2:2
-0 0:2 1:3 2:2
-0 0:2 1:3 2:2
-0 0:2 1:3 2:2
-1 0:2 1:3 2:2
diff --git a/demo/rank/toy.test.group b/demo/rank/toy.test.group
deleted file mode 100644
index 4792e70f3..000000000
--- a/demo/rank/toy.test.group
+++ /dev/null
@@ -1,2 +0,0 @@
-2
-3
diff --git a/demo/rank/toy.train b/demo/rank/toy.train
deleted file mode 100644
index cd8b6d628..000000000
--- a/demo/rank/toy.train
+++ /dev/null
@@ -1,11 +0,0 @@
-1 0:1.2 1:3 2:5.6
-0 0:2.0 1:2.3 2:5.1
-0 0:3.9 1:3 2:3.1
-0 0:2 1:3.2 2:3.4
-1 0:2.1 1:4.5 2:4.2
-0 0:1.9 1:2.8 2:3.1
-1 0:3.0 1:2.0 2:1.1
-0 0:1.9 1:1.8 2:2.1
-0 0:1.1 1:2.2 2:1.4
-1 0:2.1 1:4.1 2:4.0
-0 0:1.9 1:2.2 2:1.1
diff --git a/demo/rank/toy.train.group b/demo/rank/toy.train.group
deleted file mode 100644
index ec385ae9f..000000000
--- a/demo/rank/toy.train.group
+++ /dev/null
@@ -1,2 +0,0 @@
-6
-5
\ No newline at end of file
diff --git a/regrank/xgboost_regrank_obj.hpp b/regrank/xgboost_regrank_obj.hpp
index ed4a33dd9..abe79c330 100644
--- a/regrank/xgboost_regrank_obj.hpp
+++ b/regrank/xgboost_regrank_obj.hpp
@@ -280,11 +280,13 @@ namespace xgboost{
             virtual ~LambdaRankObj(){}
 
             virtual void SetParam(const char *name, const char *val){
-                if (!strcmp("loss_type", name)) loss_.loss_type = atoi(val);
-            }
+                if( !strcmp( "loss_type", name ) ) loss_.loss_type = atoi( val );
+                if( !strcmp( "fix_list_weight", name ) ) fix_list_weight_ = (float)atof( val );
+
+	    }
         private:
             LossType loss_;
-           
+            float fix_list_weight_;
         protected:
 
             class Triple{
@@ -372,6 +374,15 @@ namespace xgboost{
                     grad[pairs[i].first] += first_order_gradient;
                     hess[pairs[i].second] += second_order_gradient;
                     grad[pairs[i].second] -= first_order_gradient;
+                    	
+		}
+
+                if( fix_list_weight_ != 0.0f ){
+                    float scale = fix_list_weight_ / (group_index[group+1] - group_index[group]);
+                    for(unsigned j = group_index[group]; j < group_index[group+1]; ++j ){
+                        grad[j] *= scale; 
+			hess[j] *= scale;
+                    }                            
                 }
             }