average - 关于reduce part of RavenDB index, average calculation的语法问题

Question

我正在努力寻找平均列的正确语法。我所拥有的——来自 RavenDB Studio 编辑器:

map :

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 block ？我尝试了“g.totalPrice”和“g.priceAverage”，但无法识别。

感谢您的帮助!

Answer 1

Reduce部分需要像这样:

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 
}

=> 阅读部分 Common Pitfalls with MapReduce Indexes