列表上的Linq Count Group <list <string>＆gt; </list <string>

Question

我有一个对象列表，每个对象都有一个子字符串列表。我试图计算子列表中的唯一字符串。

示例对象：

private class ForumUser
{
    public List<string> RegisteredForums { get; set; }
}

举例说明

List<ForumUser> forumUsers = new List<ForumUser>
    {
        new ForumUser {RegisteredForums = {"Forum1", "Forum2"}},
        new ForumUser {RegisteredForums = {"Forum1", "Forum2", "Forum3"}},
        new ForumUser {RegisteredForums = {"Forum1", "Forum2", "Forum3", "Forum4"}},
        new ForumUser {RegisteredForums = {"Forum1", "Forum2", "Forum3", "Forum4", "Forum5"}}
    };

预期产出：

字典＆lt;'独特论坛名称'，'论坛数'＆gt;结果

Dictionary<string, int> result = forumUsers.GroupBy(&lt;your cleverness here&gt;
Forum1, 4
Forum2, 4
Forum3, 3
Forum4, 2
Forum5, 1

谢谢

Answer 1

forumUsers.SelectMany (x=> x.RegisteredForums ).GroupBy (x => x).ToDictionary (x =>x.Key,x=>x.Count())

Answer 2

forumUsers.SelectMany(f => f.RegisteredForums).GroupBy(s => s)