Github user kazk1018 commented on a diff in the pull request:
https://github.com/apache/spark/pull/3951#discussion_r23741889
--- Diff: python/pyspark/mllib/tree.py ---
@@ -383,6 +381,137 @@ def trainRegressor(cls, data,
categoricalFeaturesInfo, numTrees, featureSubsetSt
featureSubsetStrategy, impurity, maxDepth,
maxBins, seed)
+class GradientBoostedTreesModel(TreeEnsembleModel):
+ """
+ .. note:: Experimental
+
+ Represents a gradient-boosted tree model.
+ """
+
+
+class GradientBoostedTrees(object):
+ """
+ .. note:: Experimental
+
+ Learning algorithm for a gradient boosted trees model for
classification or regression.
+ """
+
+ @classmethod
+ def _train(cls, data, algo, categoricalFeaturesInfo,
+ loss, numIterations, learningRate, maxDepth):
+ first = data.first()
+ assert isinstance(first, LabeledPoint), "the data should be RDD of
LabeledPoint"
+ model = callMLlibFunc("trainGradientBoostedTreesModel", data,
algo, categoricalFeaturesInfo,
+ loss, numIterations, learningRate, maxDepth)
+ return GradientBoostedTreesModel(model)
+
+ @classmethod
+ def trainClassifier(cls, data, categoricalFeaturesInfo,
+ loss="logLoss", numIterations=100,
learningRate=0.1, maxDepth=3):
+ """
+ Method to train a gradient-boosted trees model for classification.
+
+ :param data: Training dataset: RDD of LabeledPoint. Labels should
take values {0, 1}.
+ :param categoricalFeaturesInfo: Map storing arity of categorical
+ features. E.g., an entry (n -> k) indicates that feature
+ n is categorical with k categories indexed from 0:
+ {0, 1, ..., k-1}.
+ :param loss: Loss function used for minimization during gradient
boosting.
+ (default: "logLoss")
+ :param numIterations: Number of iterations of boosting.
+ (default: 100)
+ :param learningRate: Learning rate for shrinking the contribution
of each estimator.
+ The learning rate should be between in the
interval (0, 1]
+ (default: 0.1)
+ :param maxDepth: Maximum depth of the tree. E.g., depth 0 means 1
+ leaf node; depth 1 means 1 internal node + 2 leaf nodes.
+ (default: 3)
+ :return: GradientBoostedTreesModel that can be used for prediction
+
+ Example usage:
+
+ >>> from pyspark.mllib.regression import LabeledPoint
+ >>> from pyspark.mllib.tree import GradientBoostedTrees
+ >>>
+ >>> data = [
+ ... LabeledPoint(0.0, [0.0]),
+ ... LabeledPoint(0.0, [1.0]),
+ ... LabeledPoint(1.0, [2.0]),
+ ... LabeledPoint(1.0, [3.0])
+ ... ]
+ >>>
+ >>> model =
GradientBoostedTrees.trainClassifier(sc.parallelize(data), {})
+ >>> model.numTrees()
+ 100
+ >>> model.totalNumNodes()
+ 300
+ >>> print model, # it already has newline
+ TreeEnsembleModel classifier with 100 trees
+ >>> model.predict([2.0])
+ 1.0
+ >>> model.predict([0.0])
+ 0.0
+ >>> rdd = sc.parallelize([[2.0], [0.0]])
+ >>> model.predict(rdd).collect()
+ [1.0, 0.0]
+ """
+ return cls._train(data, "classification", categoricalFeaturesInfo,
--- End diff --
@mengxr The input of BoostringStrategy.defaultParams in master branch was
changed from algo: String to Algo.fromString: Algo. So, if I fix
"classification" to "Classification", the CI test will be failed.
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