使用正则表达式从 Google BigQuery 中的字符串中提取数字

Question

我想知道是否可以在 BigQuery 中使用正则表达式从字符串中提取所有数字。

我认为以下方法有效，但只返回第一个命中 - 有没有办法提取所有命中。

我的用例是我基本上想从 url 中获取最大的数字，因为它更像是我需要加入的 post_id。

这是我所说的一个例子：

SELECT
  mystr,
  REGEXP_EXTRACT(mystr, r'(\d+)') AS nums
FROM
  (SELECT 'this is a string with some 666 numbers 999 in it 333' AS mystr),
  (SELECT 'just one number 123 in this one ' AS mystr),
  (SELECT '99' AS mystr),
  (SELECT 'another -2 example 99' AS mystr),
  (SELECT 'another-8766 example 99' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/gallery/001' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/print-preview' AS mystr)

我从中得到的结果是：

[
  {
    "mystr": "this is a string with some 666 numbers 999 in it 333",
    "nums": "666"
  },
  {
    "mystr": "just one number 123 in this one ",
    "nums": "123"
  },
  {
    "mystr": "99",
    "nums": "99"
  },
  {
    "mystr": "another -2 example 99",
    "nums": "2"
  },
  {
    "mystr": "another-8766 example 99",
    "nums": "8766"
  },
  {
    "mystr": "http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999",
    "nums": "2015"
  },
  {
    "mystr": "http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/gallery/001",
    "nums": "2015"
  },
  {
    "mystr": "http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/print-preview",
    "nums": "2015"
  }
]

Answer 1

虽然您将越来越多地在 BigQuery 中使用正则表达式，但您会意识到它的实施目前非常有限
BigQuery Regular expression functions
re2 Syntax

所以很可能很快您将不得不执行以下操作
请注意 - 对于您当前的具体示例 - 下面的代码与 @Cybril 提供的简单解决方案相比绝对没有任何好处
此解决方案更适合您在不久的将来的潜在需求
它使用 javascript UDF，从而为您提供 javascript regexp 实现的能力
BigQuery User-Defined Functions

SELECT mystr, MAX(number) as max_number FROM JS(
  // input table
  (SELECT mystr FROM
    (SELECT 'this is a string with some 666 numbers 999 in it 333' AS mystr),
    (SELECT 'just one number 123 in this one ' AS mystr),
    (SELECT '99' AS mystr),
    (SELECT 'another -2 example 99' AS mystr),
    (SELECT 'another-8766 example 99' AS mystr),
    (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999' AS mystr),
    (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/gallery/001' AS mystr),
    (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/print-preview' AS mystr)
  ) ,
  // input columns
    mystr,
  // output schema
  "[
  {name: 'mystr', type: 'string'},
  {name: 'number', type: 'string'}
  ]",
  // function
  "function(r, emit){
    var numbers = r.mystr.match(/(\d+)/g);
    for (var i=0; i < numbers.length; i++) {
      emit({
        mystr: r.mystr,
        number: numbers[i]
      });
    };  
  }"
)
GROUP BY 1

当然你也可以在UDF中移动确定最大值的逻辑来消除额外的分组

Answer 2

经过一番挖掘，我最终得到了这个解决方案：

SELECT
  mystr,
  GROUP_CONCAT(SPLIT(REGEXP_REPLACE(mystr, r'[^\d]+', ','))) AS nums
FROM
  (SELECT 'this is a string with some 666 numbers 999 in it 333' AS mystr),
  (SELECT 'just one number 123 in this one ' AS mystr),
  (SELECT '99' AS mystr),
  (SELECT 'another -2 example 99' AS mystr),
  (SELECT 'another-8766 example 99' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/gallery/001' AS mystr),
  (SELECT 'http://somedomain.com/2015/12/this-is-a-post-with-id-in-url-99999/print-preview' AS mystr)

它是如何工作的：

• 我首先使用正则表达式匹配任何非数字并用逗号替换
• 然后使用split获取结果，空结果被丢弃
• group_concat 只是在这里展示结果