linq 中的区别？

发布于 2024-10-31 12:27:34 字数 687 浏览 1 评论 0原文

我想知道如何才能实现这一目标？

我只想从对象集合中获取不同的名称，

MyObject a = new Object();
a.Name = 'One';
a.Value = '10';


MyObject b = new Object();
b.Name = 'One';
b.Value = '15';


MyObject c = new Object();
c.Name = 'Two';
c.Value = '10';

因此我只想获取名称。在这种情况下，我不关心值，只关心名称。

所以我尝试

//将所有对象添加到集合中。

myCollection.Disinct()..Select(x => new MyClassToStore() {Text = x.Name, Value = x.Name}).ToList());

但是，我需要在属性级别而不是在对象级别进行区分。所以我想要回“一”和“二”。现在我得到了“一”、“一”和“二”。

我看到一个名为 morelinq 的库，但我不确定是否应该使用它，因为它仍处于测试阶段并且似乎不再开发了。

再加上一个提取查询的整个库，我不确定它是否值得。

原文

I am wondering how can I achieve this?

I want to get only distinct names from a collection of objects

MyObject a = new Object();
a.Name = 'One';
a.Value = '10';


MyObject b = new Object();
b.Name = 'One';
b.Value = '15';


MyObject c = new Object();
c.Name = 'Two';
c.Value = '10';

So I want to get only back the name. I don't care about the value in this case just the name.

So I tried

//add all the objects to a collection.

myCollection.Disinct()..Select(x => new MyClassToStore() {Text = x.Name, Value = x.Name}).ToList());

However I need to do distinct at the property level not at the object level. So I want back "One" and "Two". Right now I get "One", "One" and "Two" back.

I see a library called morelinq but I not sure if I should use it as it still in beta and does not seem to be developed on anymore.

Plus a whole library for one extract query I am not sure if it is worth it.

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打小就很酷 2024-11-07 12:27:34

也许这样的事情可以有所帮助？

var distinctItems = items
     .GroupBy(x => x.PropertyToCompare)
     .Select(x => x.First());

Maybe something like this can help?

var distinctItems = items
     .GroupBy(x => x.PropertyToCompare)
     .Select(x => x.First());

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后eg是否自 2024-11-07 12:27:34

这将填充文本和值字段：

   myCollection.Select(x => x.Name).Distinct()
      .Select(x => new MyClassToStore { Text = x, Value = x }).ToList();

This populates both the Text and Value fields:

   myCollection.Select(x => x.Name).Distinct()
      .Select(x => new MyClassToStore { Text = x, Value = x }).ToList();

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只有影子陪我不离不弃 2024-11-07 12:27:34

如果您只想返回不同的名称，您可以使用：

myCollection.Select(x => x.Name).Distinct().ToList();

If you just want back distinct names, you can use:

myCollection.Select(x => x.Name).Distinct().ToList();

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残花月 2024-11-07 12:27:34

您可以实现您的类，以便 linq 不同运算符不使用默认的相等比较器。

class YourClass:IEquatable<YourClass> 
{

...您的实施细节。 ...

    public bool Equals(YourClass other)
    {
        if (Object.Equals(this, other))
        {
            return true;
        }
        else
        {
            if(Name == other.Name && Value == other.Value)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }

 public override int GetHashCode()
 {
     return Name.GetHashCode() ^ Value.GetHashCode();
 }

}

You can implement your class so the linq distinct operator does not use the default equality comparer.

class YourClass:IEquatable<YourClass> 
{

... Your implementation details. ...

    public bool Equals(YourClass other)
    {
        if (Object.Equals(this, other))
        {
            return true;
        }
        else
        {
            if(Name == other.Name && Value == other.Value)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }

 public override int GetHashCode()
 {
     return Name.GetHashCode() ^ Value.GetHashCode();
 }

}

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