Example of code for deduplication of C# collection based on a certain attribute of an object

When deduplication is performed based on the object's Name property, you can use the following three methods: use the Distinct method and custom comparator, use the GroupBy method of LINQ, and use the HashSet. Here are detailed code examples and explanations for each method:

1. Use the Distinct method and custom comparator:

using System;
using ;
using ;
// Custom object classpublic class Person
{
    public string Name { get; set; }
}
// Custom comparator classpublic class NameEqualityComparer : IEqualityComparer&lt;Person&gt;
{
    public bool Equals(Person x, Person y)
    {
        return  == ;
    }
    public int GetHashCode(Person obj)
    {
        return ();
    }
}
public class Program
{
    public static void Main()
    {
        // Create a collection containing duplicate objects        List&lt;Person&gt; people = new List&lt;Person&gt;()
        {
            new Person { Name = "John" },
            new Person { Name = "Jane" },
            new Person { Name = "John" },
            new Person { Name = "Alice" },
            new Person { Name = "Jane" }
        };
        // Use Distinct method and custom comparator to deduplicate        List&lt;Person&gt; distinctPeople = (new NameEqualityComparer()).ToList();
        // Output the result after deduplication        foreach (Person person in distinctPeople)
        {
            ();
        }
    }
}

explain:

In the above code, we first define a Person class with Name attribute as the basis for deduplication.
We then create a List<Person> collection containing duplicate objects.
Next, we define a custom comparator class named NameEqualityComparer, implementing the IEqualityComparer<Person> interface.
In the custom comparator class, we override the Equals method and the GetHashCode method, and compare and hash calculations based on the Name property of the Person object, respectively.
In the main program, we use the Distinct method and pass the custom comparator as a parameter to the method to implement the function of deduplication based on the Name property.
Finally, we convert the deduplication result to the List<Person> type and output the Name property of the deduplication Person object one by one.

2. Use LINQ's GroupBy method:

using System;
using ;
using ;
// Custom object classpublic class Person
{
    public string Name { get; set; }
}
public class Program
{
    public static void Main()
    {
        // Create a collection containing duplicate objects        List&lt;Person&gt; people = new List&lt;Person&gt;()
        {
            new Person { Name = "John" },
            new Person { Name = "Jane" },
            new Person { Name = "John" },
            new Person { Name = "Alice" },
            new Person { Name = "Jane" }
        };
        // Use the GroupBy method to group according to the Name attribute and select the first object of each group        List&lt;Person&gt; distinctPeople = (p =&gt; ).Select(g =&gt; ()).ToList();
        // Output the result after deduplication        foreach (Person person in distinctPeople)
        {
            ();
        }
    }
}

explain:

In the above code, we define a Person class with Name attribute as the basis for deduplication.
We then create a List<Person> collection containing duplicate objects.
Next, we use the GroupBy method to group according to the Name attribute. This returns an IEnumerable<IGrouping<string, Person>> where each group has a key (the value of the Name property) and the corresponding object collection.
Then, we use the Select method to select the first object of each group to achieve the effect of deduplication.
Finally, we convert the deduplication result to the List<Person> type and output the Name property of the deduplication Person object one by one.

3. Use HashSet:

using System;
using ;
// Custom object classpublic class Person
{
    public string Name { get; set; }
}
public class Program
{
    public static void Main()
    {
        // Create a CIn #, you can use the following methods to deduplicate the collection based on the object's Name property:1. Use the Distinct method and customize the comparator:```csharp
using System;
using ;
using ;
public class Person
{
    public string Name { get; set; }
}
public class NameEqualityComparer : IEqualityComparer&lt;Person&gt;
{
    public bool Equals(Person x, Person y)
    {
        return  == ;
    }
    public int GetHashCode(Person obj)
    {
        return ();
    }
}
public class Program
{
    public static void Main()
    {
        List&lt;Person&gt; people = new List&lt;Person&gt;()
        {
            new Person { Name = "John" },
            new Person { Name = "Jane" },
            new Person { Name = "John" },
            new Person { Name = "Alice" },
            new Person { Name = "Jane" }
        };
        List&lt;Person&gt; distinctPeople = (new NameEqualityComparer()).ToList();
        foreach (Person person in distinctPeople)
        {
            ();
        }
    }
}

In the above code, we define a Person class that contains a Name property for deduplication. Then we create a List collection containing duplicate objects. Next, we define a NameEqualityComparer class, implementing the IEqualityComparer interface, where the Equals method is used to compare whether the Name attribute is equal, and the GetHashCode method is used to obtain the hash code of the Name attribute. In the main program, we use the Distinct method and pass the custom comparator as a parameter to the Distinct method to implement the function of deduplication according to the Name property. Finally, we convert the deduplication result to List type and iterate over and output each character's Name property.

4. Use LINQ's GroupBy method:

using System;
using ;
using ;
public class Person
{
    public string Name { get; set; }
}
public class Program
{
    public static void Main()
    {
        List<Person> people = new List<Person>()
        {
            new Person { Name = "John" },
            new Person { Name = "Jane" },
            new Person { Name = "John" },
            new Person { Name = "Alice" },
            new Person { Name = "Jane" }
        };
        List<Person> distinctPeople = (p => ).Select(g => ()).ToList();
        foreach (Person person in distinctPeople)
        {
            ();
        }
    }
}

In the above code, we also define a Person class and create a List collection containing duplicate objects. Then, we use the GroupBy method to group according to the Name attribute and put objects with the same Name attribute into the same group. Next, we use the Select method to select the first object in each group to achieve the effect of deduplication. Finally, we convert the deduplication result to List type and iterate over and output each character's Name property.

5. Use HashSet:

using System;
using ;
public class Person
{
    public string Name { get; set; }
}
public class Program
{
    public static void Main()
    {
        List<Person> people = new List<Person>()
        {
            new Person { Name = "John" },
            new Person { Name = "Jane" },
            new Person { Name = "John" },
            new Person { Name = "Alice" },
            new Person { Name = "Jane" }
        };
        HashSet<Person> distinctPeople = new HashSet<Person>(people, new NameEqualityComparer());
        foreach (Person person in distinctPeople)
        {
            ();
        }
    }
}

In the above code, we also define a Person class and create a List collection containing duplicate objects. Then, we use the HashSet class and pass the List collection and custom comparator to the HashSet constructor to implement the function of deduplication based on the Name property. Finally, we traverse the output results after deduplication.

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