代码之家 › 专栏 › 技术社区 › mezoid

如何访问linq查询返回的分组值

grouping filtering c#-3.0 linq

2

mezoid · 技术社区 · 15 年前

我有以下代码:

List<Person> people = new List<Person>
    {
        new Person{ Id = 1, Name = "Bob"},
        new Person{ Id = 2, Name = "Joe"},
        new Person{ Id = 3, Name = "Bob"}
    };

    var peopleGroupedByName = from p in people 
                              group p by p.Name;

    //get all groups where the number of people in the group is > 1

现在我正把头撞在墙上,我想不出在谷歌搜索中使用什么关键词来为自己找到答案。

我真的很感激任何关于如何在Linq中实现这一点的帮助,因为它看起来应该非常简单。

3 回复 | 直到 15 年前

1

6

mezoid 15 年前

List<Person> people = new List<Person> {
    new Person{ Id = 1, Name = "Bob"},
    new Person{ Id = 2, Name = "Joe"},
    new Person{ Id = 3, Name = "Bob"}
};

var peopleGroupedByName = from p in people 
                          group p by p.Name into peopleGroup
                          where peopleGroup.Count() > 1
                          select peopleGroup;

//get all groups where the number of people in the group is > 1

或者, where peopleGroup.Skip(1).Any() 正如Mehrdad所建议的,自 Count() 迭代整个组的内容,并且 Skip(1).Any() Count 对于group by子句是可以的)。

_{旁白:

为了可读性,我更喜欢一致地使用

.GroupBy(...

扩展方法语法或

group ... by ... into ...

查询语法,但不是两者都有。}

2

mezoid 15 年前

var peopleGroupedByName = people.GroupBy(p => p.Name)
                                .Where(g => g.Count() > 1);

var peopleGroupedByName = from p in people 
                          group p by p.Name into g
                          where g.Count() > 1
                          select g;

3

0

Daniel Brückner 15 年前

var filtererGroups = people
    .GroupBy(p => p.Name)
    .Where(grp => grp.Count() > 1);

要按键过滤,您可以执行类似的操作。

var filtererGroups = people
    .GroupBy(p => p.Name)
    .Where(grp => grp.Key == "Bob");