在 hadoop 中处理非结构化和多行 CSV答案

【问题标题】：Process unstructured and multiple line CSV in hadoop在 hadoop 中处理非结构化和多行 CSV
【发布时间】：2014-02-19 15:21:42
【问题描述】：

我想在 Hadoop Mapreduce 中处理数据，我的数据格式低于非结构化、多行和未终止的引号。

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    3/15/2013 13:43,Mary Romeo,3,8/16/2012 22:23,"HOW TO SHORTEN LONG LINKS YOU'RE POSTING <br>
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请提供代码 sn-p 如何处理提到的数据？先谢谢了！！！！！！

【问题讨论】：

“过程”可能意味着很多东西。你想做什么，你尝试了什么？

标签： java csv hadoop mapreduce opencsv

【解决方案1】：

因为您要处理多行数据，所以您不能使用简单的TextInputFormat 来访问您的数据。因此，您需要为 CSV 文件使用自定义 InputFormat。

目前在 Hadoop 中没有内置的处理多行 CSV 文件的方法（请参阅https://issues.apache.org/jira/browse/MAPREDUCE-2208），但幸运的是 github 上有代码您可以尝试：https://github.com/mvallebr/CSVInputFormat。

就未终止的报价而言，可能有必要对数据进行预处理并首先对其进行清理。一个简单的规则是，如果引号前后没有分隔符（"），则对引号进行转义：

转义：a"b => a\"b
保持不变：a;"b 和 a";b

另一种选择是更正产生无效 CSV 的应用程序，以便以适当的方式转义数据。

【讨论】：