Question

这是我的清单

int specifiedvalue = 6.5;

名称值
A 6.5
A 6.0
B 6.5
B 6.0
C 7.75
D 7.0

我想从此列表中删除具有相同名称和不同于指定值（6.5）的值的对象，并保留其余部分。

结果应如下：

A 6.5
B 6.5
C 7.75
D 7.0

由于

Answer 1

internal class NameValue
{
    public string Name { get; set; }

    public double Value { get; set; }
}

var sourceList = new List<NameValue>
{
    new  NameValue {Name = "A", Value = 6.5},
    new  NameValue {Name = "A", Value = 6.0},
    new  NameValue {Name = "B", Value = 6.5},
    new  NameValue {Name = "B", Value = 6.0},
    new  NameValue {Name = "C", Value = 7.75},
    new  NameValue {Name = "D", Value = 7.0}
};

var result = sourceList.GroupBy(x => x.Name)
   .Select(x => new
   {
     Name = x.Key,
     Value = x.Max(y => y.Value)
   });

Answer 2

首先你写道，specifiedValue的类型是int。但是vaue是浮点数，您必须将其更改为double。

我想，你已经宣布了你的课程：

public class Lens
{
     public string Name { get; set; }
     public double Value { get; set; }

     public Lens(string name, double value)
     {
           Name = name;
           Value = value;
     }
}

这里我正在初始化对象：

double specidifedValue = 6.5;

List<Lens> pairs = new List<Lens>();
pairs.Add(new Lens("A", 6.5));
pairs.Add(new Lens("A", 6.0));
pairs.Add(new Lens("B", 6.5));
pairs.Add(new Lens("B", 6.0));
pairs.Add(new Lens("C", 7.75));
pairs.Add(new Lens("D", 7.0));

有了这个，首先我发现Name个在列表中出现过多次。然后选择值为6.5的那些。

var keysMoreThanOne = pairs.GroupBy(x => x.Name)
      .Where(x => x.Count() > 1).Select(x => x.Key).ToList();

List<Lens> filteredPairs = pairs
  .Where(x => (keysMoreThanOne.Contains(x.Name) && x.Value == specidifedValue) 
  || !keysMoreThanOne.Contains(x.Name)).ToList();

结果如您所愿。

<强>更新：

var result = new List<Lens>();
var keysMoreThanOne = pairs.GroupBy(x => x.Name).Where(x => x.Count() > 1).Select(x => x.Key).ToList();

if (specidifedValue > 0)
{
    result = pairs.Where(x => (keysMoreThanOne.Contains(x.Name) && x.Value == specidifedValue) ||
            !keysMoreThanOne.Contains(x.Name)).ToList();
}
else
{
    result = pairs.Where(x => (keysMoreThanOne.Contains(x.Name) && 
        x.Value == pairs.Where(y=> y.Name==x.Name).OrderByDescending(y=> y.Value).First().Value)
        || !keysMoreThanOne.Contains(x.Name)).ToList();
}

如何使用Linq Request获得此结果？

2 个答案: