C# 使用linq获取分组的逗号分隔值
我想要第三列“items”,其中包含分组的值C# 使用linq获取分组的逗号分隔值,c#,linq,linq-to-objects,grouping,C#,Linq,Linq To Objects,Grouping,我想要第三列“items”,其中包含分组的值 var dic = new Dictionary<string, int>(); dic.Add("a", 1); dic.Add("b", 1); dic.Add("c", 2); dic.Add("d", 3); var dCounts = (from i in dic group i by i.Value into g select new { g.Key, count = g.Count()});
var dic = new Dictionary<string, int>();
dic.Add("a", 1);
dic.Add("b", 1);
dic.Add("c", 2);
dic.Add("d", 3);
var dCounts =
(from i in dic
group i by i.Value into g
select new { g.Key, count = g.Count()});
var a = dCounts.Where(c => c.count>1 );
dCounts.Dump();
a.Dump();
我想要这些结果:
Key Count Items
1 2 a, b
2 1 c
3 1 d
您可以使用:
var dCounts =
from i in dic
group i by i.Value into g
select new { g.Key, Count = g.Count(), Values = g };
通过分组(valueg
)创建的结果具有一个属性Key
,该属性为您提供密钥,但它还实现了IEnumerable
,允许您访问组中的各个值。如果只返回g
,则可以使用foreach
迭代所有值,或者使用LINQ处理它们
下面是一个简单的转储函数来演示这一点:
foreach(var el in dCounts) {
Console.Write(" - {0}, count: {1}, values:", el.Key, el.Count);
foreach(var item in el.Values) Console.Write("{0}, ", item);
|
使用
string.Join(“,”,{array})
,传入您的密钥数组。如果使用string.Join,则获取异常(如Linq to entities)不会识别字符串。Join方法它不会;无法工作,因为EF无法识别C#方法字符串。Join()@LabLab原始问题不涉及EF。如果你有关于EF的问题,去问吧。简单地说:如果Microsoft数据团队不能参与语言集成,我也无能为力。他们用自己的不和谐来制造EF。我们在这里进行的是LINQ对话,不是EF。
from i in dic
group i.Key by i.Value into g
select new
{
g.Key,
count = g.Count(),
items = string.Join(",", g.ToArray())
});
var dCounts =
(from i in dic
group i by i.Value into g
select new { g.Key, count = g.Count(), Items = string.Join(",", g.Select(kvp => kvp.Key)) });
from i in dic
group i.Key by i.Value into g
select new
{
g.Key,
count = g.Count(),
items = string.Join(",", g.ToArray())
});