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我是Scala和Spark中的新成员。我使用回归代码(基于此链接Spark official site上):均方误差(MSE)返回一个庞大的数字
import org.apache.spark.mllib.regression.LabeledPoint
import org.apache.spark.mllib.regression.LinearRegressionModel
import org.apache.spark.mllib.regression.LinearRegressionWithSGD
import org.apache.spark.mllib.linalg.Vectors
// Load and parse the data
val data = sc.textFile("Year100")
val parsedData = data.map { line =>
val parts = line.split(',')
LabeledPoint(parts(0).toDouble, Vectors.dense(parts(1).split(' ').map(_.toDouble)))
}.cache()
// Building the model
val numIterations = 100
val stepSize = 0.00000001
val model = LinearRegressionWithSGD.train(parsedData, numIterations,stepSize)
// Evaluate model on training examples and compute training error
val valuesAndPreds = parsedData.map { point =>
val prediction = model.predict(point.features)
(point.label, prediction)
}
val MSE = valuesAndPreds.map{case(v, p) => math.pow((v - p), 2)}.mean()
println("training Mean Squared Error = " + MSE)
,我使用这里可以看到的数据集:Pastebin link。
所以我的问题是:为什么MSE等于889717.74(这是一个庞大的数字)?
编辑:正如论者建议,我想这些:
1)我改变了一步违约和MSE现在返回为NaN的
2)如果我尝试这个构造: LinearRegressionWithSGD.train (parsedData,numIterations,stepSize,intercept = True)spark-shell返回一个错误(error:not found:value True)
[pyspark Linear Regression Example from official documentation - Bad results?]的可能副本(http://stackoverflow.com/questions/33842982/pyspark-linear-regression-example-from-official-documentation-bad-results) – 2016-12-05 22:24:25