Question

我想使用HiveQL创建一个n-gram列表。我的想法是使用带有正则表达式和split函数的正则表达式-但这不起作用，

select split('This is my sentence', '(\\S+) +(?=(\\S+))');

输入是以下形式的列

|sentence                 |
|-------------------------|
|This is my sentence      |
|This is another sentence |

输出应该是：

["This is","is my","my sentence"]
["This is","is another","another sentence"]

Hive中有一个n-gram udf，但是该函数直接计算n-gram的频率-我想改为列出所有n-gram的列表。

非常感谢！

Answer 1

这可能不是最佳解决方案，但很有效。用定界符分割句子（在我的示例中是一个或多个空格或逗号），然后爆炸并连接以获取n元语法，然后使用collect_set组合n元语法数组（如果需要唯一的n元语法）或collect_list：

with src as 
(
select source_data.sentence, words.pos, words.word
  from
      (--Replace this subquery (source_data) with your table
       select stack (2,
                     'This is my sentence', 
                     'This is another sentence'
                     ) as sentence
      ) source_data 
        --split and explode words
        lateral view posexplode(split(sentence, '[ ,]+')) words as pos, word
)

select s1.sentence, collect_set(concat_ws(' ',s1.word, s2.word)) as ngrams 
      from src s1 
           inner join src s2 on s1.sentence=s2.sentence and s1.pos+1=s2.pos              
group by s1.sentence;

结果：

OK
This is another sentence        ["This is","is another","another sentence"]
This is my sentence             ["This is","is my","my sentence"]
Time taken: 67.832 seconds, Fetched: 2 row(s)

如何在Hive中生成所有n-gram

1 个答案: