Linq对列表进行分组，求和，排序

1.分组之后形成一个新的类的列表（分组过程中求和），最后又进行了一次排序

  public List<StaticForestArea> GroupForestList(List<FeatWithBSM> ListBSM)
       {
           var res = ListBSM.GroupBy(x => x.LZ).Select(x =>
                new StaticForestArea
                {           
                    LZ = x.Key,
                    Area = x.Sum(t => (t.geometry as IArea).Area),
                }).ToList();
           res = (from x in res
                  orderby (x.Area) descending
                  select x).ToList();
           return res;
       }   

      public class StaticForestArea
       {
         public  string LZ { get; set; }
         public double Area { get; set; }
       }   

　　2.简单的根据面积进行排序

 public  class FeatWithBSM
    {
        public IFeature feature { get; set; }
        public IGeometry geometry { get; set; }
        public string BSM { get; set; }
        public string LZ { get; set; }
        public string ZDGN { get; set; }
        public string TreeCategory { get; set; }
        public double ZXJL { get; set; }
       }
    }
public void OrderList(List<FeatWithBSM> ListBSM)
       {
           var res = (from x in ListBSM
                      orderby (x.geometry as IArea).Area descending
                      select x).ToList<FeatWithBSM>();
                
          this.features= res;
           
       }

　　3.对一个大列表根据标识码不同，分成一个个的小列表

 List<FeatWithBSM> featureList = searchFeatures("", layer);
group1 = featureList.GroupBy(x => x.BSM).Select(x =>
                new FeatureCate
                {
                    BSM = x.Key,
                    features = x.ToList()
                }).ToList();
public  class FeatureCate
    {
      
       public List<FeatWithBSM> features;
       public string BSM;
       public double SumArea;

       public string  ZDGN_1="-";//主导功能
       public string ZYSZ_1;//主要树种
       public string LZ_1;//林种
       public double ZXJL_1;//总蓄积量
}