Selecting from list based on multiple unique fields

Question

I currently have a list containing items which have fields: "name, description, source, title, ...". I want to dump a list from this, but solely unique based on two keys, the name and description. Basically, I don't want items from the list with the same name and the same description, but if they have different names and the same description, then it's fine.

I looked up that using

 list.select(x => x.Name).Distinct()

would give me a list with distinct name, but stacking them would violate having one of the unique keys different, and one the same.

I also took a look into hash sets, but I'm completely confused on how that works.

If anyone could help, it would be greatly appreciated.

stackoverflow.com/questions/1300088/distinct-with-lambda

Steve
– Steve

2016-01-14 21:53:51 +00:00
Commented Jan 14, 2016 at 21:53 — Steve
– Steve, Commented Jan 14, 2016 at 21:53

Kyle W · Accepted Answer · 2016-01-14 23:01:18Z

2

If you're just looking for all distinct name/description combinations:

list.Select(x => new {x.Name, x.Description}).Distinct();

answered Jan 14, 2016 at 23:01

Kyle W

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1 Comment

Steve Over a year ago

However we don't know if the OP wants also the other informations present in its items.

Community · Accepted Answer · 2017-05-23 11:59:38Z

0

You can either use the following example taken from HERE:

IEnumerable<Person> filteredList = originalList
  .GroupBy(person => person.Name)
  .Select(group => group.First());

Or use DistinctBy from MoreLINQ NuGet available HERE

edited May 23, 2017 at 11:59

CommunityBot

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answered Jan 14, 2016 at 21:59

user5766999

4 Comments

Steve Over a year ago

Why copy/pasting from another answer? Just close as duplicate or post a comment.

user5766999 Over a year ago

This answer is adapted to the OPs question, the link to the other answer is clearly included here also an alternative solution is provided so I do not believe posting a comment would be appropriate.

Steve Over a year ago

Sorry but I stand on my opinion. If you think that the link solves the problem with all the answers present there then it is a duplicate. If you think not, then a comment is enough. Just changing a variable name doesn't make this a substantial different answer. .

user5766999 Over a year ago

I think you are missing the point :-) Please read the answer and my previous comments fully.

serhiyb · Accepted Answer · 2016-01-14 22:38:07Z

0

var uniqueData = list.Select(x => new
            {
                UniqueKey = x.Name + " " + x.Description,
                Data = x,
            }).GroupBy(x => x.UniqueKey)
                .Select(g => g.First().Data)
                .ToList();

You should probably use some unique/special character/string instead of " " to make sure UniqueKey is really unique.

answered Jan 14, 2016 at 22:38

serhiyb

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