我试图创建一个RDD，但Spark没有创建它，抛出错误，粘贴如下;

data = records.map(lambda r: LabeledPoint(extract_label(r), extract_features(r)))
first_point = data.first()

Py4JJavaError                             Traceback (most recent call last)
<ipython-input-19-d713906000f8> in <module>()
----> 1 first_point = data.first()
  2 print "Raw data: " + str(first[2:])
  3 print "Label: " + str(first_point.label)
  4 print "Linear Model feature vector:\n" + str(first_point.features)
  5 print "Linear Model feature vector length: " + str(len    (first_point.features))

C:\spark\python\pyspark\rdd.pyc in first(self)
1313         ValueError: RDD is empty
1314         """
-> 1315         rs = self.take(1)
1316         if rs:
1317             return rs[0]

C:\spark\python\pyspark\rdd.pyc in take(self, num)
 1295 
 1296             p = range(partsScanned, min(partsScanned + numPartsToTry, totalParts))
-> 1297             res = self.context.runJob(self, takeUpToNumLeft, p)..................

任何帮助都将不胜感激。
谢谢你，英诺森