From 16f50dbe50ce58d3780399bbbd9ee8b8537f8144 Mon Sep 17 00:00:00 2001
From: "P. Druzhkov" <no@email>
Date: Mon, 29 Nov 2010 21:58:52 +0000
Subject: [PATCH] bug with negative class labels is fixed

---
 modules/ml/src/gbt.cpp | 44 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/modules/ml/src/gbt.cpp b/modules/ml/src/gbt.cpp
index f0e00f2b8a..2b8959fe87 100644
--- a/modules/ml/src/gbt.cpp
+++ b/modules/ml/src/gbt.cpp
@@ -215,6 +215,7 @@ CvGBTrees::train( const CvMat* _train_data, int _tflag,
     cvCopy( _responses, orig_response);
     orig_response->step = CV_ELEM_SIZE(_responses->type);
 
+	/*
     if (!is_regression)
     {
         int max_label = -1;
@@ -231,6 +232,38 @@ CvGBTrees::train( const CvMat* _train_data, int _tflag,
             if (class_labels->data.i[i])
                 class_labels->data.i[i] = ++class_count;
     }
+	*/
+	if (!is_regression)
+	{
+		class_count = 0;
+		unsigned char * mask = new unsigned char[get_len(orig_response)];
+		for (int i=0; i<get_len(orig_response); ++i)
+			mask[i] = 0;
+		for (int i=0; i<get_len(orig_response); ++i)
+			if (!mask[i])
+			{
+				class_count++;
+				for (int j=i; j<get_len(orig_response); ++j)
+					if (int(orig_response->data.fl[j]) == int(orig_response->data.fl[i]))
+						mask[j] = 1;
+			}
+		delete[] mask;
+	
+		class_labels = cvCreateMat(1, class_count, CV_32S);
+		class_labels->data.i[0] = int(orig_response->data.fl[0]);
+		int j = 1;
+		for (int i=1; i<get_len(orig_response); ++i)
+		{
+			int k = 0;
+			while ((int(orig_response->data.fl[i]) - class_labels->data.i[k]) && (k<j))
+				k++;
+			if (k == j)
+			{
+				class_labels->data.i[k] = int(orig_response->data.fl[i]);
+				j++;
+			}
+		}
+	}
 
     data->is_classifier = false;
 
@@ -443,8 +476,16 @@ void CvGBTrees::find_gradient(const int k)
                     exp_sfi += res;
                 }
                 int orig_label = int(resp_data[idx]);
+				/*
                 grad_data[idx] = (float)(!(k-class_labels->data.i[orig_label]+1)) -
                                  (float)(exp_fk / exp_sfi);
+				*/
+				int ensemble_label = 0;
+				while (class_labels->data.i[ensemble_label] - orig_label)
+					ensemble_label++;				
+				
+                grad_data[idx] = (float)(!(k-ensemble_label)) -
+                                 (float)(exp_fk / exp_sfi);
             }
         }; break;
 
@@ -772,10 +813,13 @@ float CvGBTrees::predict( const CvMat* _sample, const CvMat* _missing,
 
     delete[] sum;
 
+	/*
     int orig_class_label = -1;
     for (int i=0; i<get_len(class_labels); ++i)
         if (class_labels->data.i[i] == class_label+1)
             orig_class_label = i;
+	*/
+	int orig_class_label = class_labels->data.i[class_label];
 
     return float(orig_class_label);
 }