Exemplo n.º 1
0
        public void AdjustTreeOutputs(IChannel ch, RegressionTree tree, DocumentPartitioning partitioning,
                                      ScoreTracker previousScores)
        {
            _lo.Initialize(tree, partitioning, previousScores);
            _hi.Initialize(tree, partitioning, previousScores);
            _left.Initialize(tree, partitioning, previousScores);
            _right.Initialize(tree, partitioning, previousScores);

            _lo.Step   = _historicStepSize / _phi;
            _left.Step = _historicStepSize;

            if (_lo.Loss.CompareTo(_left.Loss) == 1) // backtrack
            {
                do
                {
                    Rotate(ref _hi, ref _left, ref _lo);
                    if (_hi.Step <= _minStepSize)
                    {
                        goto FINISHED;
                    }
                    _lo.Step = _left.Step / _phi;
                } while (_lo.Loss.CompareTo(_left.Loss) == 1);
            }
            else // extend (or stay)
            {
                _hi.Step = _historicStepSize * _phi;
                while (_hi.Loss.CompareTo(_left.Loss) == 1)
                {
                    Rotate(ref _lo, ref _left, ref _hi);
                    _hi.Step = _left.Step * _phi;
                }
            }

            if (_numPostbracketSteps > 0)
            {
                _right.Step = _lo.Step + (_hi.Step - _lo.Step) / _phi;
                for (int step = 0; step < _numPostbracketSteps; ++step)
                {
                    int cmp = _right.Loss.CompareTo(_left.Loss);
                    if (cmp == 0)
                    {
                        break;
                    }

                    if (cmp == 1) // move right
                    {
                        Rotate(ref _lo, ref _left, ref _right);
                        _right.Step = _lo.Step + (_hi.Step - _lo.Step) / _phi;
                    }
                    else // move left
                    {
                        Rotate(ref _hi, ref _right, ref _left);
                        if (_hi.Step <= _minStepSize)
                        {
                            goto FINISHED;
                        }
                        _left.Step = _hi.Step - (_hi.Step - _lo.Step) / _phi;
                    }
                }

                // prepare to return _left
                if (_right.Loss.CompareTo(_left.Loss) == 1)
                {
                    Swap(ref _left, ref _right);
                }
            }

FINISHED:
            if (_hi.Step < _minStepSize)
            {
                _left.Step = _minStepSize;
            }
            else if (_hi.Step == _minStepSize)
            {
                Swap(ref _hi, ref _left);
            }

            double bestStep = _left.Step;

            ch.Info("multiplier: {0}", bestStep);
            _historicStepSize = bestStep;
            tree.ScaleOutputsBy(bestStep);
        }