為什麼我在 rdd 中的 println 會打印元素字符串？ (Why does my println in rdd prints the string of elements?)

問題描述

為什麼我在 rdd 中的 println 會打印元素字符串？ (Why does my println in rdd prints the string of elements?)

當我嘗試打印我的 RDD 的內容時，它會打印如下所示的內容，我該如何打印內容？謝謝！

scala> lines
res15: org.apache.spark.rdd.RDD[Array[String]] = MapPartitionsRDD[3] at filter at <console>:23



scala> lines.take(5).foreach(println)

[Ljava.lang.String;@6d3db5d1
[Ljava.lang.String;@6e6be45e
[Ljava.lang.String;@6d5e0ff4
[Ljava.lang.String;@3a699444
[Ljava.lang.String;@69851a51

參考解法

方法 1:

This is because it uses the toString implementation for the given object. In this case Array prints out the type and hash. If you convert it to a List then it will be a prettier output due to List's toString implementation

scala>println(Array("foo"))
[Ljava.lang.String;HASH    

scala>println(Array("foo").toList)
List(foo)

方法 2:

Depending on how you want to print them out you can change your line that prints the elements to:

scala> lines.take(5).foreach(indvArray => indvArray.foreach(println))

(by user3180835、Justin Pihony、Greg)

參考文件

1. Why does my println in rdd prints the string of elements? (CC BY‑SA 2.5/3.0/4.0)