将JavaPairRdd写入Csv [英] Write JavaPairRdd to Csv

问题描述

JavaPairRdd具有saveAsTextfile功能，您可以使用该功能以文本格式保存数据.

JavaPairRdd has saveAsTextfile function, with which you can save data in a text format.

但是，我需要将数据另存为CSV文件，因此以后可以在Neo4j中使用它.

However what I need is to save the data as CSV file, so I can use it later with Neo4j.

我的问题是:

如何以CSV格式保存JavaPairRdd的数据?还是有一种方法可以将rdd转换为:

How to save the JavaPairRdd 's data in CSV format? Or is there a way to transform the rdd from :

Key   Value
Jack  [a,b,c]

收件人:

Key  value
 Jack  a
 Jack  b
 Jack  c

推荐答案

您应该在JavaPairRdd上使用flatMapValues函数:Pass each value in the key-value pair RDD through a flatMap function without changing the keys; this also retains the original RDD's partitioning.

You should use the flatMapValues function on your JavaPairRdd: Pass each value in the key-value pair RDD through a flatMap function without changing the keys; this also retains the original RDD's partitioning.

只需返回值，它就会在输入列表中为每个元素创建一行并保留键.

Just by returning the value it will create a line per element in the input lists preserving the keys.

  // In Java
  JavaPairRDD<Object, List<String>> input = ...;
  JavaPairRDD<Object, String> output = input.flatMapValues((Function<List<String>, Iterable<String>>) Functions.identity());

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