merge items in list from distinct value

Question

I have the following model:

class serverMaster
{
    public string vm { get; set; }
    public string bm { get; set; }
    public string incrday { get; set; }
    public string incrtime { get; set; }
    public string fullday { get; set; }
    public string fulltime { get; set; }
    public string backupgroup { get; set; }
    public serverMaster(string vm1, string bm1, string incrday1, string incrtime1, string fullday1, string fulltime1, string backupgroup1)
    {
        vm = vm1;
        bm = bm1;
        incrday = incrday1;
        incrtime = incrtime1;
        fullday = fullday1;
        fulltime = fulltime1;
        backupgroup = backupgroup1;

    }
}

and I have a data set like this:

How can I use Linq to find duplicates in the first column (so for example merge Aether) and concatenate the other fields.

I would ideally like to see output like this:

I guess you need to have a look at the MoreLinq package which has the .distinct function — Prashanth Benny, Sep 26 '17 at 05:18
You could also have a look at [this](https://codereview.stackexchange.com/questions/11121/merging-ienumerable-and-removing-duplicates). looks like you have landed in a similar situation — Prashanth Benny, Sep 26 '17 at 05:27
I should add that I'm trying to merge from a single list, not two lists. — Josh Hilditch, Sep 26 '17 at 05:36
Is it an in memory collection or to some database? If so EF? or what? In addition what are the names of the fields from the picture you added? — Gilad Green, Sep 26 '17 at 05:40
It need not be necessarily two lists to group them or perform union function. You could try it on your instance of serverMaster — Prashanth Benny, Sep 26 '17 at 05:42
It's a memory collection. I'm reading from text files and storing to a LIST: List allItems = new List(); Fields are named: Server Name, Backup Type, Incremental Day, Incremental Time, Full Backup Day, Full Backup Time, Backupgroup In that order ^ — Josh Hilditch, Sep 26 '17 at 05:43

Gilad Green · Accepted Answer · 2017-09-26T06:08:49.383

1

What you want to do is to GroupBy on the key field (by your comment and model I'm assuming it is vm and then to perform an aggregation operation for the other fields. From your sample data you want to concatenate the strings:

var result = allItems.GroupBy(item => item.vm)
                     .Select(group => new serverMaster {
                         vm = group.Key,
                         incrday = string.Join(", ", group.Select(i => i.incrday)),
                         incrtime = string.Join(", ", group.Select(i => i.incrtime)),
                         fullday = string.Join(", ", group.Select(i => i.fullday)),
                         fulltime = string.Join(", ", group.Select(i => i.fulltime)),
                         backupgroup = string.Join(", ", group.Select(i => i.backupgroup))
                     }).ToList();

As you do not have a default constructor you should:

var result = allItems.GroupBy(item => item.vm)
                     .Select(group => new serverMaster (
                         group.Key,
                         string.Join(", ", group.Select(i => i.incrday)),
                         string.Join(", ", group.Select(i => i.incrtime)),
                         string.Join(", ", group.Select(i => i.fullday)),
                         string.Join(", ", group.Select(i => i.fulltime)),
                         string.Join(", ", group.Select(i => i.backupgroup))
                     )).ToList();

You can have a look at: What's the difference between an object initializer and a constructor?

edited Sep 26 '17 at 06:08

answered Sep 26 '17 at 06:00

Gilad Green

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Looks great, but the code here "group => new serverMaster" is asking that I pass parameters. Do I add them? – Josh Hilditch Sep 26 '17 at 06:04
1

@JoshHilditch - oh true. That is because you do not have a default constructor and instead a constructor that gets all the parameters. I'll update my answer but I recommend to use object initializers instead of the constructor – Gilad Green Sep 26 '17 at 06:06
"there is no argument given that corresponds to the required formal parameter 'vm1' os serverMaster. That's what I'm getting. – Josh Hilditch Sep 26 '17 at 06:08
Oh ok. Sweet :) – Josh Hilditch Sep 26 '17 at 06:08
@JoshHilditch - see update + Have a look at naming conventions in C# for the names of the properties – Gilad Green Sep 26 '17 at 06:09
Well that's done it. Thank you, absolute legend. If I could buy you a beer, I would. That was the final piece of my puzzle which is going to save me so many hours of work. Wish I could +100 for this. Thank you. – Josh Hilditch Sep 26 '17 at 06:17
1

@JoshHilditch - haha :) I wish that sometimes too ;p but the max we can do is mark as solved and upvote :) Glad it helped – Gilad Green Sep 26 '17 at 06:19

merge items in list from distinct value

1 Answers1