1

桌子：

| User_ID |  Red | Blue | Green |  Rating |
|   a     |   23 |  33  |   42  |    99   |
|   a     |   56 |  45  |   62  |    45   |
|   a     |   23 |  49  |   28  |    67   |
|   b     |   39 |  59  |   10  |    87   |
|   b     |   18 |  28  |   59  |    38   |
|   b     |   40 |  50  |   38  |    94   |

我想要获得的结果是 user_id 的不同行，具有红色、蓝色和绿色的加权平均值 - 基于评级列。

颜色 * 评级/（a 或 b 的评级总和）

//编辑

无法理解如何做到这一点。尝试了以下但这是徒劳的尝试

   WITH
      averages AS (
      SELECT
        User_ID,
        SUM(rating) AS average
      FROM
`       project.dataset.table` 
      GROUP BY
        1)
    SELECT
      averages.User_ID,
      Red*(Rating/average),
      Blue*(rating/average),
      Green*(rating/average)
    FROM
      `project.dataset.table` a
    LEFT JOIN
      averages
    ON
      a.user_id = averages.user_id
4

2 回答 2

6

我明白了——这更像是一个数学问题。您将值乘以它们的权重，然后除以计数，而是除以权重的总和。每个组的所有内容（用户 ID）。你可以尝试类似的东西SELECT SUM(x * weight) / SUM(weight) FROM table GROUP BY ... 

WITH t AS (SELECT * FROM 
  UNNEST([
    STRUCT('a' AS userID, 23 AS red, 99 AS weight),
    STRUCT('a' AS userID, 56 AS red, 45 AS weight),
    STRUCT('a' AS userID, 23 AS red, 67 AS weight),
    STRUCT('b' AS userID, 39 AS red, 87 AS weight),
    STRUCT('b' AS userID, 18 AS red, 38 AS weight),
    STRUCT('b' AS userID, 40 AS red, 94 AS weight)
  ])
  )

SELECT
  userID,
  SUM(red*weight) / SUM(weight) weightedAvg,
  AVG(red) normalAvg
FROM
  t
GROUP BY
  userID

嗯！

于 2018-02-25T13:39:35.590 回答
4 
#standardSQL
WITH `project.dataset.table` AS (
  SELECT 'a' User_ID, 23 Red, 33 Blue, 42 Green, 99 Rating UNION ALL
  SELECT 'a', 56, 45, 62, 45 UNION ALL
  SELECT 'a', 23, 49, 28, 67 UNION ALL
  SELECT 'b', 39, 59, 10, 87 UNION ALL
  SELECT 'b', 18, 28, 59, 38 UNION ALL
  SELECT 'b', 40, 50, 38, 94 
)
SELECT User_ID,  
  CAST(SUM(Red * Rating) / SUM(Rating) AS INT64) Red,
  CAST(SUM(Blue * Rating) / SUM(Rating) AS INT64) Blue,
  CAST(SUM(Green * Rating) / SUM(Rating) AS INT64) Green
FROM `project.dataset.table` 
GROUP BY User_ID

结果 

Row User_ID Red     Blue    Green    
1   a       30      41      42   
2   b       36      50      31
于 2018-02-25T13:40:11.590 回答