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Merge branch 'master' of github.com:heibaiying/BigData-Notes

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罗祥 2019-06-04 15:00:16 +08:00
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notes/Spark_Transformation和Action算子.md
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@ -73,7 +73,7 @@ sc.parallelize(list).filter(_ >= 10).foreach(println)
### 1.3 flatMap ### 1.3 flatMap
`flatMap(func)`与`map`类似，但每一个输入的 item 会被映射成 0 个或多个输出的 items（ *func* 返回类型需要为`Seq`类型）。 `flatMap(func)`与`map`类似，但每一个输入的item会被映射成 0 个或多个输出的items（ *func* 返回类型需要为`Seq`）。
```scala ```scala
val list = List(List(1, 2), List(3), List(), List(4, 5)) val list = List(List(1, 2), List(3), List(), List(4, 5))
@ -319,7 +319,7 @@ sc.parallelize(list,numSlices = 2).aggregateByKey(zeroValue = 0,numPartitions =
(spark,7) (spark,7)
``` ```
`aggregateByKey(zeroValue = 0,numPartitions = 3)`的第二个参数`numPartitions `决定的是输出RDD的分区数量，想要验证这个问题，可以对上面代码进行改写，使用`getNumPartitions`方法获取分区数量： `aggregateByKey(zeroValue = 0,numPartitions = 3)`的第二个参数`numPartitions`决定的是输出RDD的分区数量，想要验证这个问题，可以对上面代码进行改写，使用`getNumPartitions`方法获取分区数量：
```scala ```scala
sc.parallelize(list,numSlices = 6).aggregateByKey(zeroValue = 0,numPartitions = 3)( sc.parallelize(list,numSlices = 6).aggregateByKey(zeroValue = 0,numPartitions = 3)(