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From Kai Voigt...@123.org>
Subject Re: How to sort in a WordCount
Date Sun, 17 Aug 2014 04:51:06 GMT
You need a second MapReduce job. Take your WordCount input, have the mapper swapping keys and
values, i.e. map(word, count) => (count, word), then your reducer will get the records
sorted by count. Since you won’t have too many unique words, one reducer should be fine,
and  you don’t have to worry about a more complex partitioner.


Am 17.08.2014 um 04:35 schrieb laozhao0@sina.cn:

> Hello,
> I am using mapreduce to get the frequency of words in a corpus . 
> And I want to get a descnding sorted result.
> Now  I can use Hive to sort them ,but If i use mapreduce,how can i do this ?
> Thakns.
> laozhao0@sina.cn

Kai Voigt			Am Germaniahafen 1			k@123.org
					24143 Kiel					+49 160 96683050
					Germany						@KaiVoigt

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