Hive 中的字数统计程序 [英] Word Count program in Hive

问题描述

我正在尝试学习 Hive.令人惊讶的是，我找不到如何编写简单的字数统计工作的示例.以下是正确的吗?

I'm trying to learn Hive. Surprisingly, I can't find an example of how to write a simple word count job. Is the following correct?

假设我有一个输入文件 input.tsv:

Let's say I have an input file input.tsv:

hello, world
this is an example input file

我在 Python 中创建了一个拆分器来将每一行变成单词:

I create a splitter in Python to turn each line into words:

import sys

for line in sys.stdin:
 for word in line.split():
   print word

然后我的 Hive 脚本中有以下内容:

And then I have the following in my Hive script:

CREATE TABLE input (line STRING);
LOAD DATA LOCAL INPATH 'input.tsv' OVERWRITE INTO TABLE input;

-- temporary table to hold words...
CREATE TABLE words (word STRING);

add file splitter.py;

INSERT OVERWRITE TABLE words 
  SELECT TRANSFORM(text) 
    USING 'python splitter.py' 
    AS word
  FROM input;

SELECT word, count(*) AS count FROM words GROUP BY word;

我不确定我是否遗漏了什么，或者它是否真的这么复杂.(特别是需要临时的words表吗，需要写外分器函数吗?)

I'm not sure if I'm missing something, or if it really is this complicated. (In particular, do I need the temporary words table, and do I need to write the external splitter function?)

推荐答案

如果您想要一个简单的，请参阅以下内容:

If you want a simple one see the following:

SELECT word, COUNT(*) FROM input LATERAL VIEW explode(split(text, ' ')) lTable as word GROUP BY word;

我使用横向视图来启用表值函数 (explode) 的使用，该函数采用拆分函数产生的列表并为每个值输出一个新行.在实践中，我使用包装了 IBM 的 ICU4J 分词器的 UDF.我通常不使用转换脚本，而对所有内容都使用 UDF.您不需要临时单词表.

I use a lateral view to enable the use of a table valued function (explode) which takes the list that comes out of split function and outputs a new row for every value. In practice I use a UDF that wraps IBM's ICU4J word breaker. I generally don't use transform scripts and use UDFs for everything. You don't need a temporary words table.

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