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"""
Logistic Regression With LBFGS Example.
"""
from __future__ import print_function

from pyspark import SparkContext
# $example on$
from pyspark.mllib.classification import LogisticRegressionWithLBFGS, LogisticRegressionModel
from pyspark.mllib.regression import LabeledPoint
# $example off$

if __name__ == "__main__":

    sc = SparkContext(appName="PythonLogisticRegressionWithLBFGSExample")

    # $example on$
    # Load and parse the data
    def parsePoint(line):
        values = [float(x) for x in line.split(' ')]
        return LabeledPoint(values[0], values[1:])

    data = sc.textFile("data/mllib/sample_svm_data.txt")
    parsedData = data.map(parsePoint)

    # Build the model
    model = LogisticRegressionWithLBFGS.train(parsedData)

    # Evaluating the model on training data
    labelsAndPreds = parsedData.map(lambda p: (p.label, model.predict(p.features)))
    trainErr = labelsAndPreds.filter(lambda (v, p): v != p).count() / float(parsedData.count())
    print("Training Error = " + str(trainErr))

    # Save and load model
    model.save(sc, "target/tmp/pythonLogisticRegressionWithLBFGSModel")
    sameModel = LogisticRegressionModel.load(sc,
                                             "target/tmp/pythonLogisticRegressionWithLBFGSModel")
    # $example off$