/// <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;
}
