List集合分组

1 var ArticleList = new Services.Data.SearchService().GetArticleBaseList(ref param);
2                 IEnumerable<IGrouping<string, Models.Data.ArticleBase>> Collection = ArticleList.GroupBy(p => p.YearIssue).ToList();//DBYL
3                 foreach (IGrouping<string, Models.Data.ArticleBase> info in Collection)
4                 {
5                     List<Models.Data.ArticleBase> sl = info.ToList<Models.Data.ArticleBase>();//分组后的集合                  
6                 }