/// <summary> /// 使用 IList 的扩展方法 GroupBy 来获取来自哪些省份的数据 /// </summary> /// <param name="persons"></param> /// <returns></returns> public static List<string> GetProvincesGroupBy(PersonList persons) { var result = new List<string>(); foreach (var item in persons.GroupBy(x => x.Province)) { result.Add(item.Key); } return result; }
/// <summary> /// 使用 IList 的扩展方法 GroupBy 每个省份有多少人 /// </summary> /// <param name="persons"></param> /// <returns></returns> public static List<PersonsInProvince> GetProvincesPersons(PersonList persons) { var result = new List<PersonsInProvince>(); foreach (var item in persons.GroupBy(x => x.Province)) { var data = new PersonsInProvince { ProvinceName = item.Key, Amount = item.Count() }; result.Add(data); } return result; }