Select 来自一组的唯一成员，按权重 categories/properties

Question

我有一组对象（5000 多个），具有 7 个不同的属性。两个属性是三级的，其余的是二元的。每个对象都指定了所有 7 个属性。在某些情况下，二进制属性可能会变成一元。

有时我需要 select 此集合中的前 N 个随机对象，根据每个类别中的标签频率对对象总数进行加权。

目前，我将sql服务器table中的所有数据作为对象，属性掩码对；但是，我可以根据需要以任何其他方式重新组织。

示例：

黑蓝黄(1,2,4)
圆方三角(8,16,32)
纯色color/meshed颜色(64)
虚线 contour/no 等高线 (128)
等(256)

数据为：

object1|9   <-      1001 black circle only (all other properties are 0)
object2|81  <-  101 0001 black square with solid color (all other properties are 0)
object3|148 <- 1001 0100 yellow square with dashed contour
etc.

说，我最终得到 1k 个对象，其中 600 个黑色对象、300 个黄色对象和 100 个蓝色对象。我需要 select 前 10 个对象。如果我只考虑一个属性，我将只取任意 6 个黑色、3 个黄色和 1 个蓝色对象。但我还有 6 个其他属性需要考虑并确保我有适量的圆形、正方形和三角形。等等。在这一点上，我什至不知道如何解决这个问题。

如有任何建议，我们将不胜感激。

*编辑：

我按照以下格式重新填充了数据

name | att1 | att2 | ...
obj1 |  1   |   8  | ...
obj2 |  2   |   16 | ...
obj3 |  1   |   32 | ...

有没有办法select TOP N objects weighted by each attribute?每个对象我有 7 个属性；没有空值。

谢谢！

Answer 1

它很混乱，它并不总是获取所需的确切行数或完美的分布，但它非常接近。

那么它是如何工作的：

ValuesPivotted：旋转所有不同的值并为每一行提供一个随机行号
TargetDistribution：对于每个不同的值，确定您需要多少
SelectRows：逐行检查 ValuesPivotted 中的每一行，查看是否要跳过该行，否则它会违反不同值的目标。否则增加适用于该行的每个值的总和。

DECLARE @TargetRowNum INT = 100;

WITH ValuesPivotted AS(
    SELECT O.id
         , RowNum = ROW_NUMBER() OVER (ORDER BY NEWID())
         , [0] =   CASE WHEN O.atr1 = 0   THEN 1 ELSE 0 END
         , [1] =   CASE WHEN O.atr1 = 1   THEN 1 ELSE 0 END
         , [2] =   CASE WHEN O.atr1 = 2   THEN 1 ELSE 0 END
         , [4] =   CASE WHEN O.atr2 = 4   THEN 1 ELSE 0 END
         , [8] =   CASE WHEN O.atr2 = 8   THEN 1 ELSE 0 END
         , [16] =  CASE WHEN O.atr3 = 16  THEN 1 ELSE 0 END
         , [32] =  CASE WHEN O.atr3 = 32  THEN 1 ELSE 0 END
         , [64] =  CASE WHEN O.atr4 = 64  THEN 1 ELSE 0 END
         , [128] = CASE WHEN O.atr4 = 128 THEN 1 ELSE 0 END
    FROM dbo.objects AS O
),
TargetDistribution AS (
    SELECT Target0   = ROUND(CAST(SUM([0]  ) AS FLOAT) / COUNT(*) * @TargetRowNum, 0)
         , Target1   = ROUND(CAST(SUM([1]  ) AS FLOAT) / COUNT(*) * @TargetRowNum, 0)
         , Target2   = ROUND(CAST(SUM([2]  ) AS FLOAT) / COUNT(*) * @TargetRowNum, 0)
         , Target4   = ROUND(CAST(SUM([4]  ) AS FLOAT) / COUNT(*) * @TargetRowNum, 0)
         , Target8   = ROUND(CAST(SUM([8]  ) AS FLOAT) / COUNT(*) * @TargetRowNum, 0)
         , Target16  = ROUND(CAST(SUM([16] ) AS FLOAT) / COUNT(*) * @TargetRowNum, 0)
         , Target32  = ROUND(CAST(SUM([32] ) AS FLOAT) / COUNT(*) * @TargetRowNum, 0)
         , Target64  = ROUND(CAST(SUM([64] ) AS FLOAT) / COUNT(*) * @TargetRowNum, 0)
         , Target128 = ROUND(CAST(SUM([128]) AS FLOAT) / COUNT(*) * @TargetRowNum, 0)
    FROM ValuesPivotted
),
SelectRows AS(
    SELECT VP.id
         , RowNum
         , KeepRow = 1
         , Target0    , Sum0   = [0]
         , Target1    , Sum1   = [1]
         , Target2    , Sum2   = [2]
         , Target4    , Sum4   = [4]
         , Target8    , Sum8   = [8]
         , Target16   , Sum16  = [16]
         , Target32   , Sum32  = [32]
         , Target64   , Sum64  = [64]
         , Target128  , Sum128 = [128]
    FROM ValuesPivotted AS VP
        CROSS JOIN TargetDistribution AS TD
    WHERE VP.RowNum = 1

    UNION ALL

    SELECT 
           VP.id
         , VP.RowNum
         , KeepRow = ISNULL(SkipRow.Value, 1)
         , Target0    , Sum0   = Sum0   + ISNULL(SkipRow.Value, [0]  )
         , Target1    , Sum1   = Sum1   + ISNULL(SkipRow.Value, [1]  )
         , Target2    , Sum2   = Sum2   + ISNULL(SkipRow.Value, [2]  )
         , Target4    , Sum4   = Sum4   + ISNULL(SkipRow.Value, [4]  )
         , Target8    , Sum8   = Sum8   + ISNULL(SkipRow.Value, [8]  )
         , Target16   , Sum16  = Sum16  + ISNULL(SkipRow.Value, [16] )
         , Target32   , Sum32  = Sum32  + ISNULL(SkipRow.Value, [32] )
         , Target64   , Sum64  = Sum64  + ISNULL(SkipRow.Value, [64] )
         , Target128  , Sum128 = Sum128 + ISNULL(SkipRow.Value, [128])
    FROM SelectRows AS SR
        INNER JOIN ValuesPivotted AS VP
            ON VP.RowNum = SR.RowNum + 1
        CROSS APPLY(
            SELECT  Value = 
                CASE WHEN   Sum0   + [0]   <= Target0 
                        AND Sum1   + [1]   <= Target1 
                        AND Sum2   + [2]   <= Target2 
                        AND Sum4   + [4]   <= Target4 
                        AND Sum8   + [8]   <= Target8 
                        AND Sum16  + [16]  <= Target16
                        AND Sum32  + [32]  <= Target32
                        AND Sum64  + [64]  <= Target64
                        AND Sum128 + [128] <= Target128
                    THEN NULL ELSE 0 END
        ) AS SkipRow
    WHERE  Sum0   < Target0 
        OR Sum1   < Target1 
        OR Sum2   < Target2 
        OR Sum4   < Target4 
        OR Sum8   < Target8 
        OR Sum16  < Target16
        OR Sum32  < Target32
        OR Sum64  < Target64
        OR Sum128 < Target128
)
SELECT O.*
FROM SelectRows AS SR
    INNER JOIN dbo.objects AS O
        ON SR.id = O.id
WHERE SR.KeepRow = 1
OPTION(MAXRECURSION 0)

编辑： SelectRows 中的 WHERE 子句没有做它应该做的事情，在满足所有目标时停止递归，现在它做到了。

Select 来自一组的唯一成员，按权重 categories/properties

Select unique members from a set by weighted categories/properties

sql

tsql

sql-server-2008