C# 是否有更好的LINQ查询来实现这一点?
假设我有一个简单的对象列表,每个对象都有一个人的名字和他们所扮演的角色,如下所示:C# 是否有更好的LINQ查询来实现这一点?,c#,linq,C#,Linq,假设我有一个简单的对象列表,每个对象都有一个人的名字和他们所扮演的角色,如下所示: var People = new[] { new PersonRole(){ Name = "Adam", Role = "R1" }, new PersonRole(){ Name = "Adam", Role = "R2" }, new PersonRole(){ Name = "Adam", Role = "R3" }
var People = new[] {
new PersonRole(){ Name = "Adam", Role = "R1" },
new PersonRole(){ Name = "Adam", Role = "R2" },
new PersonRole(){ Name = "Adam", Role = "R3" },
new PersonRole(){ Name = "Bob", Role = "R1" },
};
现在,有没有一种直接的方法可以根据名称和角色(显然)将其输入到词典中。我分两步来做,如下所示,但我认为还有更直接的方法
Dictionary<string, List<string>> resultLookup =
People.Select(p => p.Name).Distinct().ToDictionary(str => str, str => new List<string>());
People.ForEach(p => resultLookup[p.Name].Add(p.Role));
字典结果lookup=
People.Select(p=>p.Name).Distinct().ToDictionary(str=>str,str=>newlist());
People.ForEach(p=>resultLookup[p.Name].Add(p.Role));
谢谢 Dictionary Dictionary=people.GroupBy(p=>p.Name).ToDictionary(g=>g.Key,g=>g.Select(p=>p.Role).ToList());
Dictionary<string, List<string>> dictionary = people.GroupBy(p => p.Name).ToDictionary(g => g.Key, g => g.Select(p => p.Role).ToList());
未经测试,但我认为应该有效
编辑现在就对它进行了测试,事实上确实有效。这应该可以做到:
var people = new[] {
new { Name = "Adam", Role = "R1" },
new { Name = "Adam", Role = "R2" },
new { Name = "Adam", Role = "R3" },
new { Name = "Bob", Role = "R1" },
};
var r = from p in people
group p by p.Name
into g
select new {
Name = g.Key,
Roles = g.Select(p => p.Role).ToList()
};
var d = r.ToDictionary(k => k.Name, e => e.Roles);
您选择使用字典是因为一个人可以扮演多个角色吗?我认为只使用字典会更好。是的,一个人可以有多个rolesGroupBy——这是我想不出来的——真是太尴尬了,但是谢谢you@Adam:不客气。不知道你为什么觉得这很尴尬。这就是为什么要问你不确定的问题。你忘记了ToList
调用,OP指定他想要一个列表
,其中包含角色。+1因为没有将查询样式linq包装在括号中使用。ToDictionary
。当你把这些部分分到另一行/作业上时,就更清楚了。哦,天哪,那太好了,我只是想我忘了GroupBy。
var result = People.GroupBy(a => a.Name).ToDictionary(a => a.First().Name, b => b.Select(c => c.Role).ToList());
People
.GroupBy( p => p.Name )
.ToDictionary( p => p.Key, p => p.Select(pr => pr.Role).ToList() )
var dict = People.ToLookup(p=>p.Name, p=>p.Role)
.ToDictionary(it=>it.Key, it=>it.ToList());