add feature constraint

utils/xgboost_fmap.h

@@ -68,5 +68,56 @@ namespace xgboost{
             std::vector<Type>        types_;
         };
     }; // namespace utils
+
+    namespace utils{
+        /*! \brief feature constraint, allow or disallow some feature during training */
+        class FeatConstrain{
+        public:
+            FeatConstrain( void ){
+                default_state_ = +1;
+            }
+            /*!\brief set parameters */
+            inline void SetParam( const char *name, const char *val ){
+                int a, b;
+                if( !strcmp( name, "fban") ){
+                    this->ParseRange( val, a, b );
+                    this->SetRange( a, b, -1 );
+                }
+                if( !strcmp( name, "fpass") ){
+                    this->ParseRange( val, a, b );
+                    this->SetRange( a, b, +1 );
+                }
+                if( !strcmp( name, "fdefault") ){
+                    default_state_ = atoi( val );
+                }
+            }
+            /*! \brief whether constrain is specified */
+            inline bool HasConstrain( void ) const {
+                return state_.size() != 0 && default_state_ == 1;
+            }
+            /*! \brief whether a feature index is banned or not */
+            inline bool NotBanned( unsigned index ) const{
+                int rt = index < state_.size() ? state_[index] : default_state_;
+                if( rt == 0 ) rt = default_state_;
+                return rt == 1;
+            }
+        private:
+            inline void SetRange( int a, int b, int st ){
+                if( b > (int)state_.size() ) state_.resize( b, 0 );
+                for( int i = a; i < b; ++ i ){
+                    state_[i] = st;
+                }  
+            }
+            inline void ParseRange( const char *val, int &a, int &b ){
+                if( sscanf( val, "%d-%d", &a, &b ) == 2 ) return;
+                utils::Assert( sscanf( val, "%d", &a ) == 1 );
+                b = a + 1;
+            }
+            /*! \brief default state */
+            int default_state_;
+            /*! \brief whether the state here is, +1:pass, -1: ban, 0:default */
+            std::vector<int> state_;            
+        };
+    }; // namespace utils
 }; // namespace xgboost
 #endif // XGBOOST_FMAP_H