我正在尝试使用流畅的(即“方法”)语法编写嵌套的 GroupBy LINQ 表达式。
这是我的课程和数据:
class Person
{
public String ZipCode, Gender, Name;
}
private static List<Person> people = new List<Person>
{
new Person { ZipCode= "11111", Gender = "M", Name = "Tom" },
new Person { ZipCode= "11111", Gender = "M", Name = "Bob" },
new Person { ZipCode= "11111", Gender = "F", Name = "Nancy" },
new Person { ZipCode= "11111", Gender = "F", Name = "Lisa" },
new Person { ZipCode= "22222", Gender = "M", Name = "Dan" },
new Person { ZipCode= "33333", Gender = "F", Name = "Mary" },
new Person { ZipCode= "44444", Gender = "F", Name = "Joan" },
new Person { ZipCode= "44444", Gender = "F", Name = "Jane" },
new Person { ZipCode= "44444", Gender = "M", Name = "Bill" }
};
我想要实现的是一个按以下方式分组的对象ZipCode
然后通过Gender
within ZipCode
。就对象类型而言,我正在寻找这个:
IEnumerable<IGrouping<string, IEnumerable<IGrouping<string, Person>>>>
然后,这将允许我访问查询结果,如下所示:
foreach(var byZip in mainQuery) {
Console.WriteLine(byZip.Key); // print the ZipCode
foreach(var byGender in byZip) {
Console.WriteLine(byGender.Key) // print the Gender
foreach (Person p in byGender)
Console.WriteLine(p.Name);
}
}
再次,我希望使用流畅的符号。
根据下面杰夫的回答,这是查询和访问:
IEnumerable<IGrouping<string, IEnumerable<IGrouping<string, Person>>>> query =
people
.GroupBy(p => p.ZipCode)
.GroupBy(
keySelector: g => g.Key,
elementSelector: g => g.GroupBy(p => p.Gender)
);
foreach (IGrouping<string, IEnumerable<IGrouping<string, Person>>> byZip in query)
{
Console.WriteLine(byZip.Key); // print the ZipCode
foreach (IEnumerable<IGrouping<string, Person>> byGender in byZip)
{
foreach (IGrouping<string, Person> t in byGender)
{
Console.WriteLine(t.Key); // print the Gender
foreach (Person y in t)
Console.WriteLine(y.Name);
}
}
}