[Spark][Python]DataFrame select 操作例子
[Spark][Python]DataFrame中取出有限个记录的例子 的 继续 In [4]: peopleDF.select("age") Out[4]: DataFrame[age: bigint] In [5]: myDF=people.select("age") --------------------------------------------------------------------------- NameError Traceback (most recent call last) <ipython-input-5-b5b723b62a49> in <module>() ----> 1 myDF=people.select("age") NameError: name 'people' is not defined In [6]: myDF=peopleDF.select("age") In [7]: myDF.take(3) 17/10/05 05:13:02 INFO storage.MemoryStore: Block broadcast_5 stored as values in memory (estimated size 230.1 KB, free 871.7 KB) 17/10/05 05:13:02 INFO storage.MemoryStore: Block broadcast_5_piece0 stored as bytes in memory (estimated size 21.4 KB, free 893.1 KB) 17/10/05 05:13:02 INFO storage.BlockManagerInfo: Added broadcast_5_piece0 in memory on localhost:55073 (size: 21.4 KB, free: 208.7 MB) 17/10/05 05:13:02 INFO spark.SparkContext: Created broadcast 5 from take at <ipython-input-7-745486715568>:1 17/10/05 05:13:02 INFO storage.MemoryStore: Block broadcast_6 stored as values in memory (estimated size 251.1 KB, free 1144.2 KB) 17/10/05 05:13:02 INFO storage.MemoryStore: Block broadcast_6_piece0 stored as bytes in memory (estimated size 21.6 KB, free 1165.8 KB) 17/10/05 05:13:02 INFO storage.BlockManagerInfo: Added broadcast_6_piece0 in memory on localhost:55073 (size: 21.6 KB, free: 208.7 MB) 17/10/05 05:13:02 INFO spark.SparkContext: Created broadcast 6 from take at <ipython-input-7-745486715568>:1 17/10/05 05:13:03 INFO mapred.FileInputFormat: Total input paths to process : 1 17/10/05 05:13:03 INFO spark.SparkContext: Starting job: take at <ipython-input-7-745486715568>:1 17/10/05 05:13:03 INFO scheduler.DAGScheduler: Got job 2 (take at <ipython-input-7-745486715568>:1) with 1 output partitions 17/10/05 05:13:03 INFO scheduler.DAGScheduler: Final stage: ResultStage 2 (take at <ipython-input-7-745486715568>:1) 17/10/05 05:13:03 INFO scheduler.DAGScheduler: Parents of final stage: List() 17/10/05 05:13:03 INFO scheduler.DAGScheduler: Missing parents: List() 17/10/05 05:13:03 INFO scheduler.DAGScheduler: Submitting ResultStage 2 (MapPartitionsRDD[14] at take at <ipython-input-7-745486715568>:1), which has no missing parents 17/10/05 05:13:03 INFO storage.MemoryStore: Block broadcast_7 stored as values in memory (estimated size 4.3 KB, free 1170.2 KB) 17/10/05 05:13:03 INFO storage.MemoryStore: Block broadcast_7_piece0 stored as bytes in memory (estimated size 2.5 KB, free 1172.6 KB) 17/10/05 05:13:03 INFO storage.BlockManagerInfo: Added broadcast_7_piece0 in memory on localhost:55073 (size: 2.5 KB, free: 208.7 MB) 17/10/05 05:13:03 INFO spark.SparkContext: Created broadcast 7 from broadcast at DAGScheduler.scala:1006 17/10/05 05:13:03 INFO scheduler.DAGScheduler: Submitting 1 missing tasks from ResultStage 2 (MapPartitionsRDD[14] at take at <ipython-input-7-745486715568>:1) 17/10/05 05:13:03 INFO scheduler.TaskSchedulerImpl: Adding task set 2.0 with 1 tasks 17/10/05 05:13:03 INFO scheduler.TaskSetManager: Starting task 0.0 in stage 2.0 (TID 2, localhost, partition 0,PROCESS_LOCAL, 2149 bytes) 17/10/05 05:13:03 INFO executor.Executor: Running task 0.0 in stage 2.0 (TID 2) 17/10/05 05:13:03 INFO rdd.HadoopRDD: Input split: hdfs://localhost:8020/user/training/people.json:0+179 17/10/05 05:13:03 INFO codegen.GenerateUnsafeProjection: Code generated in 113.719806 ms 17/10/05 05:13:03 INFO executor.Executor: Finished task 0.0 in stage 2.0 (TID 2). 2235 bytes result sent to driver 17/10/05 05:13:03 INFO scheduler.DAGScheduler: ResultStage 2 (take at <ipython-input-7-745486715568>:1) finished in 0.493 s 17/10/05 05:13:03 INFO scheduler.TaskSetManager: Finished task 0.0 in stage 2.0 (TID 2) in 487 ms on localhost (1/1) 17/10/05 05:13:03 INFO scheduler.TaskSchedulerImpl: Removed TaskSet 2.0, whose tasks have all completed, from pool 17/10/05 05:13:03 INFO scheduler.DAGScheduler: Job 2 finished: take at <ipython-input-7-745486715568>:1, took 0.737231 s Out[7]: [Row(age=None), Row(age=30), Row(age=19)] In [8]: 本文转自健哥的数据花园博客园博客，原文链接：http://www.cnblogs.com/gaojian/p/7629891.html，如需转载请自行联系原作者
