Remove duplicates from a list in c#

Jose George

4y976C#

I have a category in my object how can I remove duplicates from each category if there is a duplicate existence based on each category in the list concept.

Please see my requirement below.

```
Category Name
------- -------
A 1
A 1
A 2
B 1
B 1
B 3
```

Final Result should be like

```
Category Name
------- -------
A 1
A 2
B 1
B 3
```

2 Replies

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Sachin Singh4y ago
simply use projection with distinct.
var res= yourList.Select(x=>new {
Category=x.Category,
Name=x.Name
}).Distinct();
Note:- Distinct doesn't work with Reference types, but when you apply projection with anonymous object Hashcode and Equals are overridden internally so it starts working.
Jignesh Kumar4y ago
Hi,
You can create extansion method and achieve this one,
public static class ListExtensions
    {
        public static IEnumerable DistinctByProperty(this IEnumerable items, Func property)
        {
            return items.GroupBy(property).Select(x => x.First());
        }
    }
You can access this extansion methos as below,
Public class Category
{
public int CategoryId {get;set;}
public string Name {get; set;}
}


List listCategory = new List();
var distinctList = listCategpry.Select( x => new Category
{
CategoryId  =x.CategoryId ,
Name  = x.Name
})).DistinctByProperty(m => new { m.CategoryId , m.Name }).ToList();