Spark - MLlib linear regression intercept and weight NaN [duplicate]

Question

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Spark MlLib linear regression (Linear least squares) giving random results (2 answers)

Closed 3 years ago.

I have trying to build a regression model on Spark using some custom data and the intercept and weights are always nan. This is my data:

data = [LabeledPoint(0.0, [27022.0]), LabeledPoint(1.0, [27077.0]), LabeledPoint(2.0, [27327.0]), LabeledPoint(3.0, [27127.0])]

Output:

(weights=[nan], intercept=nan)  

However, if I use this dataset (taken from Spark examples), it returns a non nan weight and intercept.

data = [LabeledPoint(0.0, [0.0]), LabeledPoint(1.0, [1.0]), LabeledPoint(3.0, [2.0]),LabeledPoint(2.0, [3.0])]

Output:

(weights=[0.798729902914], intercept=0.3027117101297481) 

This my current code

model = LinearRegressionWithSGD.train(sc.parallelize(data), intercept=True)

Am I missing something? Is it because the numbers on my data are that big? It is my first time using MLlib so I might be missing some details.

Thanks

Answer 1

MLlib linear regression is SGD based therefore you need to tweak iterations and step size, see https://spark.apache.org/docs/latest/mllib-optimization.html.

I tried your custom data like this and I got some results (in scala):

val numIterations = 20
val model = LinearRegressionWithSGD.train(sc.parallelize(data), numIterations)