List集合分组

 var ArticleList = new Services.Data.SearchService().GetArticleBaseList(ref param);
                 IEnumerable<IGrouping<string, Models.Data.ArticleBase>> Collection = ArticleList.GroupBy(p => p.YearIssue).ToList();//DBYL
                 foreach (IGrouping<string, Models.Data.ArticleBase> info in Collection)
                 {
                     List<Models.Data.ArticleBase> sl = info.ToList<Models.Data.ArticleBase>();//分组后的集合
                 }

关键是类型IEnumerable<IGrouping<string, Models.Data.ArticleBase>>的使用，然后是就是简单的遍历了