code: def saveAsLibSVMFile(data, dir):
          
          lines = data.map(lambda p: MLUtils._convert_labeled_point_to_libsvm(p))
          lines.saveAsTextFile(dir)
docs: Save labeled data in LIBSVM format.
  
          :param data: an RDD of LabeledPoint to be saved
          :param dir: directory to save the data
  
          >>> from tempfile import NamedTemporaryFile
          >>> from fileinput import input
          >>> from pyspark.mllib.regression import LabeledPoint
          >>> from glob import glob
          >>> from pyspark.mllib.util import MLUtils
          >>> examples = [LabeledPoint(1.1, Vectors.sparse(3, [(0, 1.23), (2, 4.56)])),
          ...             LabeledPoint(0.0, Vectors.dense([1.01, 2.02, 3.03]))]
          >>> tempFile = NamedTemporaryFile(delete=True)
          >>> tempFile.close()
          >>> MLUtils.saveAsLibSVMFile(sc.parallelize(examples), tempFile.name)
          >>> ''.join(sorted(input(glob(tempFile.name + "/part-0000*"))))
          '0.0 1:1.01 2:2.02 3:3.03\\n1.1 1:1.23 3:4.56\\n'