计算出一个滚动平均值，您并不总是除以总数

Question

我正在尝试计算板球击球手的滚动平均值。任何了解这项运动的人都会知道，平均值是按得分/局数计算的，除非击球手没有出局。如果击球手打了 2 局，并且其中 1 局“未出局”，则他们的平均数将计算为

runs scored innings 1 + runs scored innings 2 / 1

如果他们在两局中都出局，则计算为

runs scored innings 1 + runs scored innings 2 / 2

这很容易计算总体平均值，但我想将其计算为运行平均值。在使用循环并单独计算每行的平均值之前，我已经这样做了，但是任何人都可以建议一种使用任何内置函数的方法吗？

当前代码示例：

with cte as (
select 
Innings_Player, 
Innings_Runs_Scored, 
Innings_Date, 
CASE WHEN Innings_Runs_Scored = "DNB" THEN null WHEN Innings_Runs_Scored LIKE "%*%" THEN REPLACE(Innings_Runs_Scored,"*","") ELSE Innings_Runs_Scored END AS RunsNum,
CASE WHEN Innings_Runs_Scored LIKE "%*%" THEN 1 ELSE 0 END AS NotOutFlag,
ROW_NUMBER() OVER (PARTITION BY Innings_Player ORDER BY Innings_Date) as RN
from TABLE
where Innings_Player = "JE Root"
AND Innings_Runs_Scored IS NOT NULL
ORDER BY Innings_Date
)
,cte2 as
(
select
 *,
   SUM(CAST(RunsNum AS INT64)) OVER (PARTITION BY Innings_Player ORDER BY RN) AS RunningTotal,
   AVG(CAST(RunsNum AS INT64)) OVER (PARTITION BY Innings_Player ORDER BY RN) AS RunningAvg,
 from cte
 where runsNum IS NOT NULL AND runsNum <> "TDNB"
)

select * from cte2

结果数据集：

因此，平均值不正确。对于滚动平均值，第三行的计算应该是前三行的 innings_run_scored，除以 2 而不是 3，正如您从 NotOutFlag 中看到的那样，列表中的 3 局未出局。

类似地，第 4 行应该除以 3，第 5 行除以 4，然后由于第 6 行也没有出现，第 6 行应该除以 4，第 7 行除以 5 等等。我认为等式会是

Innings_Run_Scored / Innings - Not Out Count

Answer 1

AVG 基本上是SUM / COUNT 因为你想改变COUNT 部分我建议放弃使用AVG 功能。您可以使用SUM 和CASE 来计算NotOutFlag 是0 的情况

这样行

   AVG(CAST(RunsNum AS INT64)) OVER (PARTITION BY Innings_Player ORDER BY RN) AS RunningAvg,

会变成

   SUM(CAST(RunsNum AS INT64)) OVER (PARTITION BY Innings_Player ORDER BY RN) 
/  SUM(CASE WHEN NotOutFlag = 0 THEN 1 ELSE 0 END) OVER (PARTITION BY Innings_Player ORDER BY RN)
AS RunningAvg,

当然，您需要添加更多逻辑以避免除以 0。

CASE WHEN SUM(CASE WHEN NotOutFlag = 0 THEN 1 ELSE 0 END) OVER (PARTITION BY Innings_Player ORDER BY RN) = 0 
THEN 0 
ELSE 
SUM(CAST(RunsNum AS INT64)) OVER (PARTITION BY Innings_Player ORDER BY RN) 
/  
SUM(CASE WHEN NotOutFlag = 0 THEN 1 ELSE 0 END) OVER (PARTITION BY Innings_Player ORDER BY RN) 
END  AS RunningAvg,