如何在bigquery中获取以某个字符开头的所有单词

Question

我在 bigquery 表中有一个文本列。该列的示例记录看起来像 -

with temp as 
(
select 1 as id,"as we go forward into unchartered waters it's important to remember we are all in this together. #united #community" as input
union all
select 2 , "US cities close bars, restaurants and cinemas #Coronavirus"
)

select *
from temp

我想提取此列中以 # 开头的所有单词。稍后我想知道这些术语的频率。如何在 BigQuery 中执行此操作？

我的输出看起来像 -

id, word
1, united
1, community
2, coronavirus

Answer 1

以下是 BigQuery 标准 SQL

我想提取该列中所有以#开头的单词

#standardSQL
WITH temp AS (
  SELECT 1 AS id,"as we go forward into unchartered waters it's important to remember we are all in this together. #united #community" AS input UNION ALL
  SELECT 2 , "US cities close bars, restaurants and cinemas #Coronavirus"
)
SELECT id, word
FROM temp, UNNEST(REGEXP_EXTRACT_ALL(input, r'(?:^|\s)#([^#\s]*)')) word   

有输出

Row id  word     
1   1   united   
2   1   community    
3   2   Coronavirus    

稍后我想知道这些词的频率

#standardSQL
SELECT word, COUNT(1) frequency
FROM temp, UNNEST(REGEXP_EXTRACT_ALL(input, r'(?:^|\s)#([^#\s]*)')) word
GROUP BY word

Answer 2

您可以在不使用正则表达式的情况下执行此操作，方法是拆分单词，然后选择以您想要的方式开头的单词。例如：

SELECT
  id,
  ARRAY(SELECT TRIM(x, "#") FROM UNNEST(SPLIT(input, ' ')) as x WHERE STARTS_WITH(x,'#')) str
FROM
  temp

如果您希望主题标签是单独的行，您可以更紧密一些：

SELECT
  id,
  TRIM(x, "#") str
FROM
  temp,
  UNNEST(SPLIT(input, ' ')) x
WHERE
  STARTS_WITH(x,'#')