问题描述
我有几个无法加载的回归模型。 这是 Spark 初始化:
from pyspark.sql import SparkSession,sqlContext
from pyspark.ml.regression import DecisionTreeRegressor
spark = SparkSession.builder \
.appName("Linear Regression Model") \
.config('spark.executor.cores','2') \
.config("spark.executor.memory","5gb") \
.master("local[*]") \
.getorCreate()
sc = spark.sparkContext
这是模型拟合并成功保存:
# Decision Tree Regression
decisionTree = DecisionTreeRegressor(featuresCol = "Features",labelCol = "SalePrice",maxDepth = 15,maxBins = 32)
decisionTreeModel = decisionTree.fit(train_vector)
import os
decisionTreeModel.save(os.path.join(".",'decisionTreeModel'))
但是当我加载它时:
persistedModel = DecisionTreeRegressor.load("decisionTreeModel")
我收到此错误:
Py4JJavaError: An error occurred while calling o1201.load.
: java.lang.NoSuchMethodException: org.apache.spark.ml.regression.DecisionTreeRegressionModel.<init>(java.lang.String)
at java.lang.class.getConstructor0(Class.java:3082)
at java.lang.class.getConstructor(Class.java:1825)
at org.apache.spark.ml.util.DefaultParamsReader.load(ReadWrite.scala:468)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244)
at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357)
at py4j.Gateway.invoke(Gateway.java:282)
at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
at py4j.commands.CallCommand.execute(CallCommand.java:79)
at py4j.GatewayConnection.run(GatewayConnection.java:238)
at java.lang.Thread.run(Thread.java:748)
有人知道如何加载 PySpark 模型吗?
解决方法
错误信息不是很有帮助,但我认为加载模型的正确方法是调用模型的 load
方法,而不是估计器的方法。模型已经拟合到数据,这与估计器不同,它只包含设置/参数,但没有拟合。
所以你可以试试这个:
from pyspark.ml.regression import DecisionTreeRegressionModel
persistedModel = DecisionTreeRegressionModel.load("decisionTreeModel")
以下是加载估算器与加载模型的比较,供您参考:
from pyspark.ml.regression import DecisionTreeRegressor,DecisionTreeRegressionModel
decisionTree = DecisionTreeRegressor(featuresCol = "Features",labelCol = "SalePrice",maxDepth = 15,maxBins = 32)
decisionTree.save('tree')
persistedEstimator = DecisionTreeRegressor.load('tree')
decisionTreeModel = decisionTree.fit(df)
decisionTreeModel.save('model')
persistedModel = DecisionTreeRegressionModel.load('model')