[英]How to group by a new string in LINQ
Here is some code I have written. 这是我写的一些代码。 The variable aa has a set of values that are not distinct.
变量aa具有一组不同的值。 I would like for aa to be a set of distinct values so I need a "group by".
我希望aa是一组不同的值,所以我需要一个“分组依据”。 The problem I have is that the "new" variable is a string created on the fly and I cannot group by it before I have done the new.
我的问题是“ new”变量是一个动态创建的字符串,在完成新操作之前我无法对其进行分组。
List<KeyValuePair<String, int>> x = new List<KeyValuePair<string, int>>();
x.Add(new KeyValuePair<String, int>("one", 1));
x.Add(new KeyValuePair<String, int>("two", 2));
List<KeyValuePair<String, int>> y = new List<KeyValuePair<string, int>>();
y.Add(new KeyValuePair<String, int>("one", 1));
y.Add(new KeyValuePair<String, int>("xxx", 12));
var aa = from xx in x
from yy in y
select new { AA = string.Format("a={0}, b={1}", xx, yy) };
Could use Distinct()
可以使用
Distinct()
//This var can be exchanged with IEnumerable<string>
var aa = (from xx in x
from yy in y
select string.Format("a={0}, b={1}", xx, yy))
.Distinct();
if you want to make list x's content excusive over y and or y's content exclusive over x the you have the command Except()
如果要使列表x的内容对y有意义,或者要使y的内容对x独占,则可以使用命令
Except()
var aa1 = from xx in x
from yy in y
select new { AA = string.Format("a={0}, b={1}", xx, yy) };
/*RESULT:
a=[one, 1], b=[one, 1]
a=[one, 1], b=[xxx, 12]
a=[two, 2], b=[one, 1]
a=[two, 2], b=[xxx, 12]*/
var aa2 = from xx in x
from yy in y.Except(x)
select new { AA = string.Format("a={0}, b={1}", xx, yy) };
/*RESULT:
a=[one, 1], b=[xxx, 12]
a=[two, 2], b=[xxx, 12]*/
var aa3 = from xx in x.Except(y)
from yy in y
select new { AA = string.Format("a={0}, b={1}", xx, yy) };
/*RESULT:
a=[two, 2], b=[one, 1]
a=[two, 2], b=[xxx, 12]*/
var aa4 = from xx in x.Except(y)
from yy in y.Except(x)
select new { AA = string.Format("a={0}, b={1}", xx, yy) };
/*RESULT:
a=[two, 2], b=[xxx, 12]*/
Yes you can you can materialize with aa.ToList() and then group by. 是的,您可以使用aa.ToList()实现,然后分组。 But you should at least say what do you expect as output
但是您至少应该说出您期望输出什么
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