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author | Joseph K. Bradley <joseph.kurata.bradley@gmail.com> | 2014-08-02 13:07:17 -0700 |
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committer | Xiangrui Meng <meng@databricks.com> | 2014-08-02 13:07:17 -0700 |
commit | 3f67382e7c9c3f6a8f6ce124ab3fcb1a9c1a264f (patch) | |
tree | 1a39b613599d552f2fbdd1679f78f205887d1698 /mllib | |
parent | e09e18b3123c20e9b9497cf606473da500349d4d (diff) | |
download | spark-3f67382e7c9c3f6a8f6ce124ab3fcb1a9c1a264f.tar.gz spark-3f67382e7c9c3f6a8f6ce124ab3fcb1a9c1a264f.tar.bz2 spark-3f67382e7c9c3f6a8f6ce124ab3fcb1a9c1a264f.zip |
[SPARK-2478] [mllib] DecisionTree Python API
Added experimental Python API for Decision Trees.
API:
* class DecisionTreeModel
** predict() for single examples and RDDs, taking both feature vectors and LabeledPoints
** numNodes()
** depth()
** __str__()
* class DecisionTree
** trainClassifier()
** trainRegressor()
** train()
Examples and testing:
* Added example testing classification and regression with batch prediction: examples/src/main/python/mllib/tree.py
* Have also tested example usage in doc of python/pyspark/mllib/tree.py which tests single-example prediction with dense and sparse vectors
Also: Small bug fix in python/pyspark/mllib/_common.py: In _linear_predictor_typecheck, changed check for RDD to use isinstance() instead of type() in order to catch RDD subclasses.
CC mengxr manishamde
Author: Joseph K. Bradley <joseph.kurata.bradley@gmail.com>
Closes #1727 from jkbradley/decisiontree-python-new and squashes the following commits:
3744488 [Joseph K. Bradley] Renamed test tree.py to decision_tree_runner.py Small updates based on github review.
6b86a9d [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
affceb9 [Joseph K. Bradley] * Fixed bug in doc tests in pyspark/mllib/util.py caused by change in loadLibSVMFile behavior. (It used to threshold labels at 0 to make them 0/1, but it now leaves them as they are.) * Fixed small bug in loadLibSVMFile: If a data file had no features, then loadLibSVMFile would create a single all-zero feature.
67a29bc [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
cf46ad7 [Joseph K. Bradley] Python DecisionTreeModel * predict(empty RDD) returns an empty RDD instead of an error. * Removed support for calling predict() on LabeledPoint and RDD[LabeledPoint] * predict() does not cache serialized RDD any more.
aa29873 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
bf21be4 [Joseph K. Bradley] removed old run() func from DecisionTree
fa10ea7 [Joseph K. Bradley] Small style update
7968692 [Joseph K. Bradley] small braces typo fix
e34c263 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
4801b40 [Joseph K. Bradley] Small style update to DecisionTreeSuite
db0eab2 [Joseph K. Bradley] Merge branch 'decisiontree-bugfix2' into decisiontree-python-new
6873fa9 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
225822f [Joseph K. Bradley] Bug: In DecisionTree, the method sequentialBinSearchForOrderedCategoricalFeatureInClassification() indexed bins from 0 to (math.pow(2, featureCategories.toInt - 1) - 1). This upper bound is the bound for unordered categorical features, not ordered ones. The upper bound should be the arity (i.e., max value) of the feature.
93953f1 [Joseph K. Bradley] Likely done with Python API.
6df89a9 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
4562c08 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
665ba78 [Joseph K. Bradley] Small updates towards Python DecisionTree API
188cb0d [Joseph K. Bradley] Merge branch 'decisiontree-bugfix' into decisiontree-python-new
6622247 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
b8fac57 [Joseph K. Bradley] Finished Python DecisionTree API and example but need to test a bit more.
2b20c61 [Joseph K. Bradley] Small doc and style updates
1b29c13 [Joseph K. Bradley] Merge branch 'decisiontree-bugfix' into decisiontree-python-new
584449a [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
dab0b67 [Joseph K. Bradley] Added documentation for DecisionTree internals
8bb8aa0 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-bugfix
978cfcf [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-bugfix
6eed482 [Joseph K. Bradley] In DecisionTree: Changed from using procedural syntax for functions returning Unit to explicitly writing Unit return type.
376dca2 [Joseph K. Bradley] Updated meaning of maxDepth by 1 to fit scikit-learn and rpart. * In code, replaced usages of maxDepth <-- maxDepth + 1 * In params, replace settings of maxDepth <-- maxDepth - 1
e06e423 [Joseph K. Bradley] Merge branch 'decisiontree-bugfix' into decisiontree-python-new
bab3f19 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
59750f8 [Joseph K. Bradley] * Updated Strategy to check numClassesForClassification only if algo=Classification. * Updates based on comments: ** DecisionTreeRunner *** Made dataFormat arg default to libsvm ** Small cleanups ** tree.Node: Made recursive helper methods private, and renamed them.
52e17c5 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-bugfix
f5a036c [Joseph K. Bradley] Merge branch 'decisiontree-bugfix' into decisiontree-python-new
da50db7 [Joseph K. Bradley] Added one more test to DecisionTreeSuite: stump with 2 continuous variables for binary classification. Caused problems in past, but fixed now.
8e227ea [Joseph K. Bradley] Changed Strategy so it only requires numClassesForClassification >= 2 for classification
cd1d933 [Joseph K. Bradley] Merge branch 'decisiontree-bugfix' into decisiontree-python-new
8ea8750 [Joseph K. Bradley] Bug fix: Off-by-1 when finding thresholds for splits for continuous features.
8a758db [Joseph K. Bradley] Merge branch 'decisiontree-bugfix' into decisiontree-python-new
5fe44ed [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-python-new
2283df8 [Joseph K. Bradley] 2 bug fixes.
73fbea2 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into decisiontree-bugfix
5f920a1 [Joseph K. Bradley] Demonstration of bug before submitting fix: Updated DecisionTreeSuite so that 3 tests fail. Will describe bug in next commit.
f825352 [Joseph K. Bradley] Wrote Python API and example for DecisionTree. Also added toString, depth, and numNodes methods to DecisionTreeModel.
Diffstat (limited to 'mllib')
3 files changed, 82 insertions, 2 deletions
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala b/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala index 7d912737b8..1d5d3762ed 100644 --- a/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala +++ b/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala @@ -19,6 +19,8 @@ package org.apache.spark.mllib.api.python import java.nio.{ByteBuffer, ByteOrder} +import scala.collection.JavaConverters._ + import org.apache.spark.annotation.DeveloperApi import org.apache.spark.api.java.{JavaRDD, JavaSparkContext} import org.apache.spark.mllib.classification._ @@ -29,6 +31,11 @@ import org.apache.spark.mllib.linalg.{Matrix, SparseVector, Vector, Vectors} import org.apache.spark.mllib.random.{RandomRDDGenerators => RG} import org.apache.spark.mllib.recommendation._ import org.apache.spark.mllib.regression._ +import org.apache.spark.mllib.tree.configuration.Algo._ +import org.apache.spark.mllib.tree.configuration.Strategy +import org.apache.spark.mllib.tree.DecisionTree +import org.apache.spark.mllib.tree.impurity.{Entropy, Gini, Impurity, Variance} +import org.apache.spark.mllib.tree.model.DecisionTreeModel import org.apache.spark.mllib.stat.Statistics import org.apache.spark.mllib.stat.correlation.CorrelationNames import org.apache.spark.mllib.util.MLUtils @@ -473,6 +480,76 @@ class PythonMLLibAPI extends Serializable { } /** + * Java stub for Python mllib DecisionTree.train(). + * This stub returns a handle to the Java object instead of the content of the Java object. + * Extra care needs to be taken in the Python code to ensure it gets freed on exit; + * see the Py4J documentation. + * @param dataBytesJRDD Training data + * @param categoricalFeaturesInfoJMap Categorical features info, as Java map + */ + def trainDecisionTreeModel( + dataBytesJRDD: JavaRDD[Array[Byte]], + algoStr: String, + numClasses: Int, + categoricalFeaturesInfoJMap: java.util.Map[Int, Int], + impurityStr: String, + maxDepth: Int, + maxBins: Int): DecisionTreeModel = { + + val data = dataBytesJRDD.rdd.map(deserializeLabeledPoint) + + val algo: Algo = algoStr match { + case "classification" => Classification + case "regression" => Regression + case _ => throw new IllegalArgumentException(s"Bad algoStr parameter: $algoStr") + } + val impurity: Impurity = impurityStr match { + case "gini" => Gini + case "entropy" => Entropy + case "variance" => Variance + case _ => throw new IllegalArgumentException(s"Bad impurityStr parameter: $impurityStr") + } + + val strategy = new Strategy( + algo = algo, + impurity = impurity, + maxDepth = maxDepth, + numClassesForClassification = numClasses, + maxBins = maxBins, + categoricalFeaturesInfo = categoricalFeaturesInfoJMap.asScala.toMap) + + DecisionTree.train(data, strategy) + } + + /** + * Predict the label of the given data point. + * This is a Java stub for python DecisionTreeModel.predict() + * + * @param featuresBytes Serialized feature vector for data point + * @return predicted label + */ + def predictDecisionTreeModel( + model: DecisionTreeModel, + featuresBytes: Array[Byte]): Double = { + val features: Vector = deserializeDoubleVector(featuresBytes) + model.predict(features) + } + + /** + * Predict the labels of the given data points. + * This is a Java stub for python DecisionTreeModel.predict() + * + * @param dataJRDD A JavaRDD with serialized feature vectors + * @return JavaRDD of serialized predictions + */ + def predictDecisionTreeModel( + model: DecisionTreeModel, + dataJRDD: JavaRDD[Array[Byte]]): JavaRDD[Array[Byte]] = { + val data = dataJRDD.rdd.map(xBytes => deserializeDoubleVector(xBytes)) + model.predict(data).map(serializeDouble) + } + + /** * Java stub for mllib Statistics.corr(X: RDD[Vector], method: String). * Returns the correlation matrix serialized into a byte array understood by deserializers in * pyspark. @@ -597,4 +674,5 @@ class PythonMLLibAPI extends Serializable { val s = getSeedOrDefault(seed) RG.poissonVectorRDD(jsc.sc, mean, numRows, numCols, parts, s).map(serializeDoubleVector) } + } diff --git a/mllib/src/main/scala/org/apache/spark/mllib/tree/configuration/Strategy.scala b/mllib/src/main/scala/org/apache/spark/mllib/tree/configuration/Strategy.scala index 5c65b537b6..fdad4f029a 100644 --- a/mllib/src/main/scala/org/apache/spark/mllib/tree/configuration/Strategy.scala +++ b/mllib/src/main/scala/org/apache/spark/mllib/tree/configuration/Strategy.scala @@ -56,7 +56,8 @@ class Strategy ( if (algo == Classification) { require(numClassesForClassification >= 2) } - val isMulticlassClassification = numClassesForClassification > 2 + val isMulticlassClassification = + algo == Classification && numClassesForClassification > 2 val isMulticlassWithCategoricalFeatures = isMulticlassClassification && (categoricalFeaturesInfo.size > 0) diff --git a/mllib/src/test/scala/org/apache/spark/mllib/tree/DecisionTreeSuite.scala b/mllib/src/test/scala/org/apache/spark/mllib/tree/DecisionTreeSuite.scala index 546a132559..8665a00f3b 100644 --- a/mllib/src/test/scala/org/apache/spark/mllib/tree/DecisionTreeSuite.scala +++ b/mllib/src/test/scala/org/apache/spark/mllib/tree/DecisionTreeSuite.scala @@ -48,7 +48,8 @@ class DecisionTreeSuite extends FunSuite with LocalSparkContext { requiredMSE: Double) { val predictions = input.map(x => model.predict(x.features)) val squaredError = predictions.zip(input).map { case (prediction, expected) => - (prediction - expected.label) * (prediction - expected.label) + val err = prediction - expected.label + err * err }.sum val mse = squaredError / input.length assert(mse <= requiredMSE) |