average - 关于减少 RavenDB 索引的一部分，平均计算的语法问题

Question

我正在努力使用平均列的正确语法。我所拥有的——来自 RavenDB Studio 编辑器：

地图：

from area in docs.Level5_AdministrativeAreas
select new 
{
     area.NAME_4,
     totalPrice = area.pricePerSquareMetre,
     areaCount = 1,
     priceAverage = 0
}

减少：

from result in results
group result by new { result.NAME_4 } into g
select new 
{
   NAME_4 = g.Key.NAME_4,
   totalPrice = g.Sum(x => x.totalPrice),
   areaCount = g.Sum(x => x.areaCount),
   priceAverage = totalPrice / areaCount
}

计数和总价计算正确，但我不知道如何引用totalPrice和areaCount.

是否需要额外的选择块？我尝试了“g.totalPrice”和“g.priceAverage”，但它没有被识别。

谢谢您的帮助 ！

Answer 1

Reduce 部分需要是这样的：

减少：

from result in results
group result by new { result.NAME_4 } into g
let theCount = g.Sum(x => x.areaCount)
let theTotal = g.Sum(x => x.totalPrice)
select new 
{
   NAME_4 = g.Key.NAME_4,
   totalPrice = theTotal,
   areaCount = theCount ,
   priceAverage = theTotal / theCount 
}

=> 阅读MapReduce 索引的常见陷阱部分

Answer 2

可能不理想，但这有效（谈论不只见树木不见森林......）

priceAverage = g.Sum(x => x.totalPrice) / g.Sum(x => x.areaCount)