Python pyspark DecisionTreeRegressor用法及代碼示例

>>> from pyspark.ml.linalg import Vectors
>>> df = spark.createDataFrame([
...     (1.0, Vectors.dense(1.0)),
...     (0.0, Vectors.sparse(1, [], []))], ["label", "features"])
>>> dt = DecisionTreeRegressor(maxDepth=2)
>>> dt.setVarianceCol("variance")
DecisionTreeRegressor...
>>> model = dt.fit(df)
>>> model.getVarianceCol()
'variance'
>>> model.setLeafCol("leafId")
DecisionTreeRegressionModel...
>>> model.depth
1
>>> model.numNodes
3
>>> model.featureImportances
SparseVector(1, {0: 1.0})
>>> model.numFeatures
1
>>> test0 = spark.createDataFrame([(Vectors.dense(-1.0),)], ["features"])
>>> model.predict(test0.head().features)
0.0
>>> result = model.transform(test0).head()
>>> result.prediction
0.0
>>> model.predictLeaf(test0.head().features)
0.0
>>> result.leafId
0.0
>>> test1 = spark.createDataFrame([(Vectors.sparse(1, [0], [1.0]),)], ["features"])
>>> model.transform(test1).head().prediction
1.0
>>> dtr_path = temp_path + "/dtr"
>>> dt.save(dtr_path)
>>> dt2 = DecisionTreeRegressor.load(dtr_path)
>>> dt2.getMaxDepth()
2
>>> model_path = temp_path + "/dtr_model"
>>> model.save(model_path)
>>> model2 = DecisionTreeRegressionModel.load(model_path)
>>> model.numNodes == model2.numNodes
True
>>> model.depth == model2.depth
True
>>> model.transform(test1).head().variance
0.0
>>> model.transform(test0).take(1) == model2.transform(test0).take(1)
True
>>> df3 = spark.createDataFrame([
...     (1.0, 0.2, Vectors.dense(1.0)),
...     (1.0, 0.8, Vectors.dense(1.0)),
...     (0.0, 1.0, Vectors.sparse(1, [], []))], ["label", "weight", "features"])
>>> dt3 = DecisionTreeRegressor(maxDepth=2, weightCol="weight", varianceCol="variance")
>>> model3 = dt3.fit(df3)
>>> print(model3.toDebugString)
DecisionTreeRegressionModel...depth=1, numNodes=3...