我想从人员列表中按组列出报告类别的列表
class Report
{
public string Country { get; set; }
public double SumAge { get; set; }
}
class Person
{
public int Age { get; set; }
public string Name { get; set; }
public string Country { get; set; }
}
var list = new List<Person>
{
new Person {Age = 35, Country = "Spain", Name = "John"},
new Person {Age = 45, Country = "Spain", Name = "Alex"},
new Person {Age = 55, Country = "Hungary", Name = "Bob"},
new Person {Age = 23, Country = "Spain", Name = "Eve"},
new Person {Age = 39, Country = "India", Name = "Rose"},
new Person {Age = 25, Country = "India", Name = "Peter"},
new Person {Age = 51, Country = "Hungary", Name = "Rob"},
new Person {Age = 23, Country = "India", Name = "Jeff"},
};
list.GroupBy(p => p.Country, p => p)
.Select(p => new Report
{
Country = p.Key,
SumAge = p.Sum() //????
});
select语句中有问题，我怎么计算年龄？
您需要指定要汇总的属性：
var res = list.GroupBy(p => p.Country, p => p)
.Select(p => new Report
{
Country = p.Key,
SumAge = p.Sum(x => x.Age)
});
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