我设法让我的决策树分类器适用于基于RDD的API,但现在我正试图切换到Spark中基于Dataframes的API。在带有字符串字段的spark中使用决策树分类器的数据框
我有一个这样的数据集(但有更多的字段):
国家,目的地,时间,标签
Belgium, France, 10, 0
Bosnia, USA, 120, 1
Germany, Spain, 30, 0
首先,我加载一个数据帧我的csv文件:
val data = session.read
.format("org.apache.spark.csv")
.option("header", "true")
.csv("/home/Datasets/data/dataset.csv")
然后,我将字符串列转换为数字列
val stringColumns = Array("country", "destination")
val index_transformers = stringColumns.map(
cname => new StringIndexer()
.setInputCol(cname)
.setOutputCol(s"${cname}_index")
)
然后我组装我的所有功能集成到一个单一的载体,使用VectorAssembler,像这样:
val assembler = new VectorAssembler()
.setInputCols(Array("country_index", "destination_index", "duration_index"))
.setOutputCol("features")
我我的数据分割为训练和测试:
val Array(trainingData, testData) = data.randomSplit(Array(0.7, 0.3))
然后创建我DecisionTree分类
val dt = new DecisionTreeClassifier()
.setLabelCol("label")
.setFeaturesCol("features")
然后我使用一个管道进行所有转换
val pipeline = new Pipeline()
.setStages(Array(index_transformers, assembler, dt))
我训练我的模型,并用它来预测:
val model = pipeline.fit(trainingData)
val predictions = model.transform(testData)
,但我得到了一些错误,我不明白:
当我运行我的代码这样的,我有这样的错误:
[error] found : Array[org.apache.spark.ml.feature.StringIndexer]
[error] required: org.apache.spark.ml.PipelineStage
[error] .setStages(Array(index_transformers, assembler,dt))
因此,我所做的是,我添加了一个管道index_transformers VAL和Val汇编权前右后:
val index_pipeline = new Pipeline().setStages(index_transformers)
val index_model = index_pipeline.fit(data)
val df_indexed = index_model.transform(data)
和我的训练集和测试集,我的新df_indexed数据框中使用,我从我的管道用汇编和DT
val Array(trainingData, testData) = df_indexed.randomSplit(Array(0.7, 0.3))
val pipeline = new Pipeline()
.setStages(Array(assembler,dt))
去除index_transformers我得到这个错误:
Exception in thread "main" java.lang.IllegalArgumentException: Data type StringType is not supported.
它基本上说我在字符串上使用VectorAssembler,而我告诉它在df_indexed上使用它,它现在有一个数字column_index,但它似乎并没有在vectorAssembler中使用它,我只是不清楚和..
谢谢
编辑
现在我几乎设法得到它的工作:
val data = session.read
.format("org.apache.spark.csv")
.option("header", "true")
.csv("/home/hvfd8529/Datasets/dataOINIS/dataset.csv")
val stringColumns = Array("country_index", "destination_index", "duration_index")
val stringColumns_index = stringColumns.map(c => s"${c}_index")
val index_transformers = stringColumns.map(
cname => new StringIndexer()
.setInputCol(cname)
.setOutputCol(s"${cname}_index")
)
val assembler = new VectorAssembler()
.setInputCols(stringColumns_index)
.setOutputCol("features")
val labelIndexer = new StringIndexer()
.setInputCol("label")
.setOutputCol("indexedLabel")
val Array(trainingData, testData) = data.randomSplit(Array(0.7, 0.3))
// Train a DecisionTree model.
val dt = new DecisionTreeClassifier()
.setLabelCol("indexedLabel")
.setFeaturesCol("features")
.setImpurity("entropy")
.setMaxBins(1000)
.setMaxDepth(15)
// Convert indexed labels back to original labels.
val labelConverter = new IndexToString()
.setInputCol("prediction")
.setOutputCol("predictedLabel")
.setLabels(labelIndexer.labels())
val stages = index_transformers :+ assembler :+ labelIndexer :+ dt :+ labelConverter
val pipeline = new Pipeline()
.setStages(stages)
// Train model. This also runs the indexers.
val model = pipeline.fit(trainingData)
// Make predictions.
val predictions = model.transform(testData)
// Select example rows to display.
predictions.select("predictedLabel", "label", "indexedFeatures").show(5)
// Select (prediction, true label) and compute test error.
val evaluator = new MulticlassClassificationEvaluator()
.setLabelCol("indexedLabel")
.setPredictionCol("prediction")
.setMetricName("accuracy")
val accuracy = evaluator.evaluate(predictions)
println("accuracy = " + accuracy)
val treeModel = model.stages(2).asInstanceOf[DecisionTreeClassificationModel]
println("Learned classification tree model:\n" + treeModel.toDebugString)
只是现在我有一个错误,说这样的:
value labels is not a member of org.apache.spark.ml.feature.StringIndexer
,我不明白,因为我在跟随在火花DOC例子:/
我仍然有同样的错误:( 我也曾尝试\t \t VAL阶段= index_transformers:+汇编:+ dt的 VAL管道=新管道() \t \t .setStages(级) 但不工作:不支持数据类型StringType:java.lang.IllegalArgumentException异常 –