c# 常见的取中值（去掉最大值，最小值，剩下的值求平均）

 public object Getmedianaverage(int number,  DateTime startdate, DateTime enddate)
        {
            #region 中值平均
            number = 5;
            string sql = string.Format("SELECT ID,DEEP_DISPLACEMENT_X_VALUE,ACQUISITION_DATETIME FROM  [dbo].[T_THEMES_DEFORMATION_DEEP_DISPLACEMENT]  WHERE ACQUISITION_DATETIME BETWEEN '{0}' AND '{1}' ", "2020-05-15 10:55:13", "2020-05-15 20:55:13");
            DataTable Datalist = SqlHelper.ExecuteDataSetText(sql, null).Tables[0];
            List<Medianaavg> oldMedianaavg = new List<Medianaavg>();
            // 原数组
            foreach (DataRow item in Datalist.Rows)
            {
                Medianaavg avginfo = new Medianaavg();
                avginfo.id = int.Parse(item["ID"].ToString());
                avginfo.value = double.Parse(item["DEEP_DISPLACEMENT_X_VALUE"].ToString());
                avginfo.date = DateTime.Parse(item["ACQUISITION_DATETIME"].ToString());
                oldMedianaavg.Add(avginfo);
            }
            //新数组
            List<NewMedianaavg> NewMedianaavg = new List<NewMedianaavg>();
            foreach (var index in oldMedianaavg)
            {
                NewMedianaavg Newinfo = new NewMedianaavg();
                Newinfo.id = index.id;
                Newinfo.value = index.value;
                Newinfo.date = index.date;
                NewMedianaavg.Add(Newinfo);
            }
            List<Beforeorder> orderlist = new List<Beforeorder>();
            int c = 0;
            for (int i = 0; i <oldMedianaavg.Count; i++)
            {
                //排序前添加
                for (int a = 0 +c; a < number +c; a++)
                {
                    Beforeorder orderinfo = new Beforeorder();
                    orderinfo.id = oldMedianaavg[a].id;
                    orderinfo.value = oldMedianaavg[a].value;
                    orderinfo.date = oldMedianaavg[a].date;
                    orderlist.Add(orderinfo);
                }
                //排序计算
                var query = from items in orderlist orderby items.value select items;           
                List<afterorder> afterorderlist = new List<afterorder>(); //满足传过来条件，排序后 放入数据的临时数组
               //排序后的值添加到数组
                foreach (var item in query)
                {
                    afterorder afterinfo = new afterorder();
                    afterinfo.id = item.id;
                    afterinfo.value = item.value;
                    afterinfo.date = item.date;
                    afterorderlist.Add(afterinfo);
                }
                //去掉最小值
                afterorderlist.RemoveAt(afterorderlist.Count - (afterorderlist.Count));
                // 去掉最大值
                afterorderlist.RemoveAt(afterorderlist.Count - 1);
                double aftersum = 0.0;
                double afteravg = 0.0;
                for (int d = 0; d < afterorderlist.Count; d++)
                {
                    aftersum += afterorderlist[d].value;
                    
                }
                afteravg = Math.Round(Math.Round(aftersum, 6) / afterorderlist.Count,6);
                if (number + c < NewMedianaavg.Count)
                { 
                NewMedianaavg[number + c].value = afteravg;
                }
                //清空
                orderlist = new List<Beforeorder>();
                //清空排序后的数组使一直保存五条数据
                afterorderlist = new List<afterorder>();
                c++;
            }

            MedianaavgCollection collection = new MedianaavgCollection();
            collection.oldMediandata = oldMedianaavg;
            collection.newMediandata = NewMedianaavg;
            return collection;
            #endregion
        }