title: IndexError: string index out of range pyspark
body: <p>I am very new to spark programming. I am trying to implement a map and reduceByKey to the following data set with 15 fields.</p>
  
  <pre><code>rdd=sc.parallelize([
  ("West",  "Apple",  2.0, 10,2.0, 10,2.0, 10,2.0, 10,2.0, 10,2.0,2.0, 10),
  ("West",  "Apple",  3.0, 10,2.0, 10,2.0, 10,2.0, 10,2.0, 10,2.0, 10,2.0])
  </code></pre>
  
  <p>This is my map function where i am trying to create a tuple with multiple keys and values</p>
  
  <pre><code>rdd1 = rdd.map(lambda x: ((x[0],x[1]),(x[2],x[3],x[4],x[5],x[6],x[7],x[8],x[9],x[10],x[11],x[12],x[13],x[14])))
  </code></pre>
  
  <p>Next step i am trying to reduceByKey (to implement a sql like aggregate on values in the above tuple)</p>
  
  <pre><code>rdd2 = rdd1.reduceByKey(lambda x,y: (x[1]+','+y[1]))
  </code></pre>
  
  <p>This reduce function works as expected for the tuple index value 0-4, but when i try the tuple index value 5-14, I get the IndexError.</p>
  
  <pre><code>rdd2 = rdd1.reduceByKey(lambda x,y: (x[10]+','+y[10]))
  Traceback (most recent call last):
  File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  File "/opt/spark/python/pyspark/rdd.py", line 1277, in take
  res = self.context.runJob(self, takeUpToNumLeft, p, True)
  File "/opt/spark/python/pyspark/context.py", line 897, in runJob
  allowLocal)
  File "/opt/spark/python/lib/py4j-0.8.2.1-src.zip/py4j/java_gateway.py",   line 538, in __call__
  File "/opt/spark/python/lib/py4j-0.8.2.1-src.zip/py4j/protocol.py", line 300, in get_return_value
  py4j.protocol.Py4JJavaError15/08/28 01:23:22 WARN TaskSetManager: Lost task 1.0 in stage 78.0 (TID 91, localhost): TaskKilled (killed  intentionally)
  : An error occurred while calling  z:org.apache.spark.api.python.PythonRDD.runJob.
  : org.apache.spark.SparkException: Job aborted due to stage failure:   Task 0 in stage 78.0 failed 1 times, most recent failure: Lost task 0.0 in   stage 78.0 (TID 90, localhost):   org.apache.spark.api.python.PythonException: Traceback (most recent call   last):
  File "/opt/spark/python/lib/pyspark.zip/pyspark/worker.py", line 111, in main
  process()
  File "/opt/spark/python/lib/pyspark.zip/pyspark/worker.py", line 106, in process
  serializer.dump_stream(func(split_index, iterator), outfile)
  File "/opt/spark/python/pyspark/rdd.py", line 2330, in pipeline_func
  return func(split, prev_func(split, iterator))
  File "/opt/spark/python/pyspark/rdd.py", line 2330, in pipeline_func
  return func(split, prev_func(split, iterator))
  File "/opt/spark/python/pyspark/rdd.py", line 316, in func
  return f(iterator)
  File "/opt/spark/python/pyspark/rdd.py", line 1758, in combineLocally
  merger.mergeValues(iterator)
  File "/opt/spark/python/lib/pyspark.zip/pyspark/shuffle.py", line 268, in mergeValues
  d[k] = comb(d[k], v) if k in d else creator(v)
  File "&lt;stdin&gt;", line 1, in &lt;lambda&gt;
  IndexError: string index out of range
  
  at org.apache.spark.api.python.PythonRDD$$anon$1.read(PythonRDD.scala:138)
  at org.apache.spark.api.python.PythonRDD$$anon$1.&lt;init&gt;(PythonRDD.scala:179)
  at org.apache.spark.api.python.PythonRDD.compute(PythonRDD.scala:97)
  at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
  at org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
  at org.apache.spark.api.python.PairwiseRDD.compute(PythonRDD.scala:315)
  at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
  at org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
  at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:70)
  at org.apache.spark.scheduler.Task.run(Task.scala:70)
  at    org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:213)
  at      java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
  at  java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
  at java.lang.Thread.run(Thread.java:695)
  
  Driver stacktrace:
  at org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$failJobAndIndependentStages(DAGScheduler.scala:1273)
  at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1264)
  at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1263)
  at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
  at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
  at org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:1263)
  at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:730)
  at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:730)
  at scala.Option.foreach(Option.scala:236)
  at org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:730)
  at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1457)
  at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1418)
  at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:48)
  </code></pre>
  
  <p>This looks like a very non trivial error. I am not sure if this error is because of hardware of my machine or my implementation of reduce function or something to do with spark.</p>
  
  <p>Any sort of help is appreciated.</p>