C# Lamda 表达式 GroupBy实现数据统计分组

Posted 2022-11-24 Walter_lee2008

   List<scoreruleA> list = new List<scoreruleA>()
           
                new scoreruleA() id=1,scoreitem="语文",score=92 ,
                new scoreruleA() id=1,scoreitem="语文",score=90 ,
                new scoreruleA() id=2,scoreitem="语文",score=95 ,
                new scoreruleA() id=3,scoreitem="数学",score=21 ,
                new scoreruleA() id=3,scoreitem="数学",score=34 ,
                new scoreruleA() id=6,scoreitem="数学",score=45 ,
            ;

1.实现按照 学科 分数 分组。          

  var aa =  list.GroupBy(a => a.scoreitem).Select(g => (new aabb=g, year = g.Key, avg = g.Average(m => m.score), max = g.Max(n => n.score), count = g.Count() ));

2.实现按照 班级 学科 分数 分组。
   var bb = list.GroupBy(a => new a.id, a.scoreitem ).Select(g => (new aabb = g, year = g.Key, avg = g.Average(m => m.score), max = g.Max(n => n.score), count = g.Count() ));