我有一个LINQ查询,从过去12个月取得的收视率平均:如何获得在Linq查询分组结果
{Date: {Year: 2016, Month: 11}, Rating: [4]}
{Date: {Year: 2016, Month: 10}, Rating: [5, 5, 4]}
{Date: {Year: 2016, Month: 9}, Rating: []}
{Date: {Year: 2016, Month: 8}, Rating: []}
{Date: {Year: 2016, Month: 7}, Rating: []}
{Date: {Year: 2016, Month: 6}, Rating: []}
{Date: {Year: 2016, Month: 5}, Rating: []}
{Date: {Year: 2016, Month: 4}, Rating: []}
{Date: {Year: 2016, Month: 3}, Rating: []}
{Date: {Year: 2016, Month: 2}, Rating: []}
{Date: {Year: 2016, Month: 1}, Rating: []}
{Date: {Year: 2015, Month: 12}, Rating: []}
:
var ratingsByMonth =
from month in Enumerable.Range(0, 12)
let key = new { Year = DateTime.Now.AddMonths(-month).Year, Month = DateTime.Now.AddMonths(-month).Month }
join groupedRating in ratings on key
equals new
{
groupedRating.RatingDate.Year,
groupedRating.RatingDate.Month
} into g
select new {
Date = key,
Rating = g.Select(x=>x.Rating)
};
ratingsByMonth从我的数据集中返回以下JSON
但是,我试图将评分字段汇总为平均值。我已经试过这样:
return Json(new
{
Average = ratingsByMonth.Average(x=>x.Rating),
Dates = ratingsByMonth.Select(x => Date)
});
,但我得到的平均强调了以下错误 - 行:
无法隐式转换类型 “System.Collections.Generic.IEnumerable”到“长? “
,我寻找的输出是:
{Date: {Year: 2016, Month: 11}, Rating: 4}
{Date: {Year: 2016, Month: 10}, Rating: 3.5}
{Date: {Year: 2016, Month: 9}, Rating: 0}
{Date: {Year: 2016, Month: 8}, Rating: 0}
{Date: {Year: 2016, Month: 7}, Rating: 0}
{Date: {Year: 2016, Month: 6}, Rating: 0}
{Date: {Year: 2016, Month: 5}, Rating: 0}
{Date: {Year: 2016, Month: 4}, Rating: 0}
{Date: {Year: 2016, Month: 3}, Rating: 0}
{Date: {Year: 2016, Month: 2}, Rating: 0}
{Date: {Year: 2016, Month: 1}, Rating: 0}
{Date: {Year: 2015, Month: 12}, Rating: 0}
编辑:
试图改变以下几点:
return Json(new
{
Average = ratingsByMonth.Select(x => x.Rating).SelectMany(x => x).Average(),
Dates = ratingsByMonth.Select(x => x.Date.Month)
});
然而,这只是给了我一个整个数据集的“平均”值,而不是每个日期的平均值。
编辑:
下面是示例数据:
RatingID Rating RatingDate
5 5 2016-10-09 20:11:29.590
11 0 2016-10-09 20:14:42.503
21 5 2016-10-09 20:24:15.667
60 4 2016-10-28 11:01:21.220
64 4 2016-11-03 16:30:47.657
所以对于十一月平均应该是4,和十月应该是3.5(5 + 0 + 5 + 4/4)
还有就是JSON和您在LINQ显示什么之间的不匹配。是Date还是GroupCriteria?给出示例数据同时显示所需的输出。我认为你可能正在寻找一个SelectMany,然后平均 – Nkosi
谢谢,已更新 – Evonet