ClickHouse 数组 - 在数组中找到最长的重复数字链

Posted 2023-03-25

【中文标题】ClickHouse 数组 - 在数组中找到最长的重复数字链

【英文标题】：ClickHouse array - find a longest chain of repeating number in array

【发布时间】：2019-10-22 10:21:00

【问题描述】：

在 Clickhouse 中，我有一列包含 Int16 元素的数组。我正在寻找一种方法来找到最长的重复数字 1 链。 例如，在数组 [0,1,1,1,5,1,1,1,1,1,2] 中，重复 1 的最长链是 5 个元素。有没有办法用现有的功能做到这一点？

【问题讨论】：

上面的“可能重复”是错误的。该链接适用于 javascript 中的出现。这里的 OP 在 Clickhouse 中提问。

【参考方案1】：

试试这个查询：

SELECT
    /* The source number. */
    data.1 AS number,
    /* The source array. */
    data.2 AS array,
    /* Number the values ​​in each chain. */
    arrayCumSumNonNegative((x, index) -> x = number ? 1 : -index, array, arrayEnumerate(array)) AS partiallySumArray,
    arrayReduce('max', partiallySumArray) AS result
FROM
(
    /* test data set */
    SELECT arrayJoin([
      /**/
      (1, []), 
      (1, [0, 2, 2, 2, 5]), 
      (1, [0, 1, 1, 1, 5, 1, 1, 1, 1, 1,2]), 
      (1, [1, 1, 1, 2, 3, 4, 5, 1, 1]), 
      (1, [-5, 100, 1, 1, 0, 1, 1, 1]),
      (1, [1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0]),
      /**/
      (5, []), 
      (5, [0, 2, 2, 2, 55]),       
      (5, [5, 5, 10, 300, 5, 77, 5])
      ]) AS data
)
FORMAT Vertical

/* Result:

Row 1:
──────
number:            1
array:             []
partiallySumArray: []
result:            0

Row 2:
──────
number:            1
array:             [0,2,2,2,5]
partiallySumArray: [0,0,0,0,0]
result:            0

Row 3:
──────
number:            1
array:             [0,1,1,1,5,1,1,1,1,1,2]
partiallySumArray: [0,1,2,3,0,1,2,3,4,5,0]
result:            5

Row 4:
──────
number:            1
array:             [1,1,1,2,3,4,5,1,1]
partiallySumArray: [1,2,3,0,0,0,0,1,2]
result:            3

Row 5:
──────
number:            1
array:             [-5,100,1,1,0,1,1,1]
partiallySumArray: [0,0,1,2,0,1,2,3]
result:            3

Row 6:
──────
number:            1
array:             [1,1,0,1,1,1,1,1,1,0,0]
partiallySumArray: [1,2,0,1,2,3,4,5,6,0,0]
result:            6

Row 7:
──────
number:            5
array:             []
partiallySumArray: []
result:            0

Row 8:
──────
number:            5
array:             [0,2,2,2,55]
partiallySumArray: [0,0,0,0,0]
result:            0

Row 9:
───────
number:            5
array:             [5,5,10,300,5,77,5]
partiallySumArray: [1,2,0,0,1,0,1]
result:            2
*/

【讨论】：

很高兴为您提供帮助 ;)