public void AddTree(RegressionTree tree) => _trees.Add(tree);
public void AddTreeAt(RegressionTree tree, int index) => _trees.Insert(index, tree);
public IPredictorProducing <float> CombineModels(IEnumerable <IPredictorProducing <float> > models)
{
_host.CheckValue(models, nameof(models));
var ensemble = new Ensemble();
int modelCount = 0;
int featureCount = -1;
bool binaryClassifier = false;
foreach (var model in models)
{
modelCount++;
var predictor = model;
_host.CheckValue(predictor, nameof(models), "One of the models is null");
var calibrated = predictor as CalibratedPredictorBase;
double paramA = 1;
if (calibrated != null)
{
_host.Check(calibrated.Calibrator is PlattCalibrator,
"Combining FastTree models can only be done when the models are calibrated with Platt calibrator");
predictor = calibrated.SubPredictor;
paramA = -(calibrated.Calibrator as PlattCalibrator).ParamA;
}
var tree = predictor as FastTreePredictionWrapper;
if (tree == null)
{
throw _host.Except("Model is not a tree ensemble");
}
foreach (var t in tree.TrainedEnsemble.Trees)
{
var bytes = new byte[t.SizeInBytes()];
int position = -1;
t.ToByteArray(bytes, ref position);
position = -1;
var tNew = new RegressionTree(bytes, ref position);
if (paramA != 1)
{
for (int i = 0; i < tNew.NumLeaves; i++)
{
tNew.SetOutput(i, tNew.LeafValues[i] * paramA);
}
}
ensemble.AddTree(tNew);
}
if (modelCount == 1)
{
binaryClassifier = calibrated != null;
featureCount = tree.InputType.ValueCount;
}
else
{
_host.Check((calibrated != null) == binaryClassifier, "Ensemble contains both calibrated and uncalibrated models");
_host.Check(featureCount == tree.InputType.ValueCount, "Found models with different number of features");
}
}
var scale = 1 / (double)modelCount;
foreach (var t in ensemble.Trees)
{
for (int i = 0; i < t.NumLeaves; i++)
{
t.SetOutput(i, t.LeafValues[i] * scale);
}
}
switch (_kind)
{
case PredictionKind.BinaryClassification:
if (!binaryClassifier)
{
return(new FastTreeBinaryPredictor(_host, ensemble, featureCount, null));
}
var cali = new PlattCalibrator(_host, -1, 0);
return(new FeatureWeightsCalibratedPredictor(_host, new FastTreeBinaryPredictor(_host, ensemble, featureCount, null), cali));
case PredictionKind.Regression:
return(new FastTreeRegressionPredictor(_host, ensemble, featureCount, null));
case PredictionKind.Ranking:
return(new FastTreeRankingPredictor(_host, ensemble, featureCount, null));
default:
_host.Assert(false);
throw _host.ExceptNotSupp();
}
}
public virtual void AddScores(RegressionTree tree, double multiplier)
{
tree.AddOutputsToScores(Dataset, Scores, multiplier);
SendScoresUpdatedMessage();
}
public RegressionTreeVisualizator(RegressionTree tree, Chart chart)
{
Tree = tree;
RegressionChart = chart;
}
/// <summary>
/// Constructs partitioning object based on the documents and RegressionTree splits
/// NOTE: It has been optimized for speed and multiprocs with 10x gain on naive LINQ implementation
/// </summary>
public DocumentPartitioning(RegressionTree tree, Dataset dataset)
: this(dataset.NumDocs, tree.NumLeaves)
{
using (Timer.Time(TimerEvent.DocumentPartitioningConstruction))
{
// figure out which leaf each document belongs to
// NOTE: break it up into NumThreads chunks. This minimizes the number of re-computations necessary in
// the row-wise indexer.
int innerLoopSize = 1 + dataset.NumDocs / BlockingThreadPool.NumThreads; // +1 is to make sure we don't have a few left over at the end
// figure out the exact number of chunks, needed in pathological cases when NumDocs < NumThreads
int numChunks = dataset.NumDocs / innerLoopSize;
if (dataset.NumDocs % innerLoopSize != 0)
{
++numChunks;
}
var perChunkDocumentLists = new List <int> [numChunks][];
// REVIEW: This partitioning doesn't look optimal.
// Probably make sence to investigate better ways of splitting data?
var actions = new Action[(int)Math.Ceiling(1.0 * dataset.NumDocs / innerLoopSize)];
var actionIndex = 0;
for (int docStart = 0; docStart < dataset.NumDocs; docStart += innerLoopSize)
{
var fromDoc = docStart;
var toDoc = Math.Min(docStart + innerLoopSize, dataset.NumDocs);
var chunkIndex = docStart / innerLoopSize;
actions[actionIndex++] = () =>
{
Contracts.Assert(perChunkDocumentLists[chunkIndex] == null);
var featureBins = dataset.GetFeatureBinRowwiseIndexer();
List <int>[] perLeafDocumentLists = Enumerable.Range(0, tree.NumLeaves)
.Select(x => new List <int>(innerLoopSize / tree.NumLeaves))
.ToArray();
for (int d = fromDoc; d < toDoc; d++)
{
int leaf = tree.GetLeaf(featureBins[d]);
perLeafDocumentLists[leaf].Add(d);
}
perChunkDocumentLists[chunkIndex] = perLeafDocumentLists;
};
}
Parallel.Invoke(new ParallelOptions {
MaxDegreeOfParallelism = BlockingThreadPool.NumThreads
}, actions);
// establish leaf starts and document counts
_leafCount = Enumerable.Range(0, tree.NumLeaves)
.Select(leaf => Enumerable.Range(0, perChunkDocumentLists.Length)
.Select(thread => perChunkDocumentLists[thread][leaf].Count)
.Sum())
.ToArray();
var cumulativeLength = _leafCount.CumulativeSum <int>().Take(tree.NumLeaves - 1);
_leafBegin = Enumerable.Range(0, 1).Concat(cumulativeLength).ToArray();
// move all documents that belong to the same leaf together
Contracts.Assert(_documents.Length == _leafBegin[tree.NumLeaves - 1] + _leafCount[tree.NumLeaves - 1]);
actions = new Action[tree.NumLeaves];
actionIndex = 0;
for (int leaf = 0; leaf < tree.NumLeaves; leaf++)
{
var l = leaf;
actions[actionIndex++] = () =>
{
int documentPos = _leafBegin[l];
for (int chunkIndex = 0; chunkIndex < perChunkDocumentLists.Length; chunkIndex++)
{
foreach (int d in perChunkDocumentLists[chunkIndex][l])
{
_documents[documentPos++] = d;
}
perChunkDocumentLists[chunkIndex][l] = null;
}
};
}
Parallel.Invoke(new ParallelOptions {
MaxDegreeOfParallelism = BlockingThreadPool.NumThreads
}, actions);
}
}
public void Initialize(RegressionTree tree, DocumentPartitioning partitioning, ScoreTracker previousScores)
{
_tree = tree;
_partitioning = partitioning;
_previousScores = previousScores;
}
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);
}
public TreeEnsemble GetModel(int[] categoricalFeatureBoudaries)
{
TreeEnsemble res = new TreeEnsemble();
string modelString = GetModelString();
string[] lines = modelString.Split('\n');
int i = 0;
for (; i < lines.Length;)
{
if (lines[i].StartsWith("Tree="))
{
Dictionary <string, string> kvPairs = new Dictionary <string, string>();
++i;
while (!lines[i].StartsWith("Tree=") && lines[i].Trim().Length != 0)
{
string[] kv = lines[i].Split('=');
Contracts.Check(kv.Length == 2);
kvPairs[kv[0].Trim()] = kv[1].Trim();
++i;
}
int numLeaves = int.Parse(kvPairs["num_leaves"], CultureInfo.InvariantCulture);
int numCat = int.Parse(kvPairs["num_cat"], CultureInfo.InvariantCulture);
if (numLeaves > 1)
{
var leftChild = Str2IntArray(kvPairs["left_child"], ' ');
var rightChild = Str2IntArray(kvPairs["right_child"], ' ');
var splitFeature = Str2IntArray(kvPairs["split_feature"], ' ');
var threshold = Str2DoubleArray(kvPairs["threshold"], ' ');
var splitGain = Str2DoubleArray(kvPairs["split_gain"], ' ');
var leafOutput = Str2DoubleArray(kvPairs["leaf_value"], ' ');
var decisionType = Str2UIntArray(kvPairs["decision_type"], ' ');
var defaultValue = GetDefalutValue(threshold, decisionType);
var categoricalSplitFeatures = new int[numLeaves - 1][];
var categoricalSplit = new bool[numLeaves - 1];
if (categoricalFeatureBoudaries != null)
{
// Add offsets to split features.
for (int node = 0; node < numLeaves - 1; ++node)
{
splitFeature[node] = categoricalFeatureBoudaries[splitFeature[node]];
}
}
if (numCat > 0)
{
var catBoundaries = Str2IntArray(kvPairs["cat_boundaries"], ' ');
var catThreshold = Str2UIntArray(kvPairs["cat_threshold"], ' ');
for (int node = 0; node < numLeaves - 1; ++node)
{
if (GetIsCategoricalSplit(decisionType[node]))
{
int catIdx = (int)threshold[node];
var cats = GetCatThresholds(catThreshold, catBoundaries[catIdx], catBoundaries[catIdx + 1]);
categoricalSplitFeatures[node] = new int[cats.Length];
// Convert Cat thresholds to feature indices.
for (int j = 0; j < cats.Length; ++j)
{
categoricalSplitFeatures[node][j] = splitFeature[node] + cats[j] - 1;
}
splitFeature[node] = -1;
categoricalSplit[node] = true;
// Swap left and right child.
int t = leftChild[node];
leftChild[node] = rightChild[node];
rightChild[node] = t;
}
else
{
categoricalSplit[node] = false;
}
}
}
RegressionTree tree = RegressionTree.Create(numLeaves, splitFeature, splitGain,
threshold.Select(x => (float)(x)).ToArray(), defaultValue.Select(x => (float)(x)).ToArray(), leftChild, rightChild, leafOutput,
categoricalSplitFeatures, categoricalSplit);
res.AddTree(tree);
}
else
{
RegressionTree tree = new RegressionTree(2);
var leafOutput = Str2DoubleArray(kvPairs["leaf_value"], ' ');
if (leafOutput[0] != 0)
{
// Convert Constant tree to Two-leaf tree, avoid being filter by TLC.
var categoricalSplitFeatures = new int[1][];
var categoricalSplit = new bool[1];
tree = RegressionTree.Create(2, new int[] { 0 }, new double[] { 0 },
new float[] { 0 }, new float[] { 0 }, new int[] { -1 }, new int[] { -2 }, new double[] { leafOutput[0], leafOutput[0] },
categoricalSplitFeatures, categoricalSplit);
}
res.AddTree(tree);
}
}
else
{
++i;
}
}
return(res);
}
public void AdjustTreeOutputs(IChannel ch, RegressionTree tree, DocumentPartitioning partitioning, ScoreTracker trainingScores)
{
}
private RegressionTree createTree(string name, Test testSample)
{
RegressionTree tree = new RegressionTree(testSample, name, Penalty);
return(tree);
}