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Add rows with same ID together after SELECT using LINQ

Hi all I am using LINQ to query a table like this:
AlbumID | Spotify | iTunes
--------------------------
5 | 12 | 4
5 | 18 | 6
6 | 10 | 8
I would like to add together rows with the same unique AlbumID, I am aware of GroupBy but that groups together all similar IDs so I used Where that uses albumID (an input arg in this example it could be 5)
var platformArray = Context.Analytics.Where(x => x.AlbumID == albumId).Select(s => new
{
Id = s.AlbumID,
Spotify = s.SpotifyClicks,
Itunes = s.ItunesClicks
});
But when I print out to debug console, it does not combine the unique ID's
foreach (var item in platformArray)
{
Debug.WriteLine(item.Id);
Debug.WriteLine(item.Spotify);
Debug.WriteLine(item.Itunes);
}
I see (added arrows for clarity):
5 <-ID
12 <-Spotify
4 <-ITunes
5 <-ID
18 <-Spotify
6 <-ITunes
How can I reformat my LINQ code to print out something like:
5 <-ID
30 <-Spotify
10 <-Itunes
Thanks!
EDIT: adding my Analytic Class
public class Analytic
{
private object p1;
private object p2;
private object p3;
public Analytic(object p1, object p2, object p3)
{
this.p1 = p1;
this.p2 = p2;
this.p3 = p3;
}
[Key]
public int Id { get; set; }
public int AlbumID { get; set; }
public int SpotifyClicks { get; set; }
public int ItunesClicks { get; set; }
public virtual Album Album { get; set; }
}

Try below code:
var List = from element in prod
group element by new { element.Id } into g
select new yourClass
(
Id = g.First().ID,
Spotify = g.Sum(s => s.Spotify)
Itunes = g.Sum(s => s.Itunes)
);

So I managed to figure this out from the help of Hasan's comment on my original post and some additional fixes:
var query = Context.Analytics
.Where(x => x.AlbumID == albumId)
.GroupBy(c => c.AlbumID)
.Select(
g =>
new
{
Id = g.Key,
Spotify = g.Sum(s => s.SpotifyClicks),
ITunes = g.Sum(s => s.ItunesClicks),
}
);
This only queries for my specific albumID and sums together all rows with that specific ID!
Thanks everyone

So after you have grouped your Albums into groups of Albums with the same AlbumId, you want to transform all Albums in the group into one object, containing the common AlbumId, the total of all Spotify of all Albums in your group, and the total of all iTunes of all Albums in your group.
var result = albums.GroupBy(album => album.AlbumId)
// from every group, make one element with the sum of Spotify and sum of itunes:
.Select(group => new
{
AlbumId = group.Key,
Spotify = group.Select(groupElement => groupElement.Spotify).Sum(),
ITunes = group.Select(groupElement => groupElement.Itunes).Sum(),
});
Simple comme bonjour!

How to left join to another left join

I have a table that holds stock items. These stock items have the following properties
public class StockItem
{
public int BrandId { get; set; }
public int ModelId { get; set; }
public decimal Price { get; set; }
public int StoreId { get; set; }
}
Where StoreId can be either 1 (Store A) or 2 (Store B)
I want to group these items to get the following result
BrandId
ModelId
Count in Store A
count in Store B
I have used group by clause before but not in this way. How should I write the linQ statement to accomplish my task?
To summarize I have the following records
Id BrandId ModelId Price StoreId
=========================================
1 1 1 11 1
2 1 1 11 1
3 1 2 12 1
4 1 2 12 2
5 1 1 11 2
and trying to get the following result
BrandId ModelId CountInStoreA CountInStoreB
=================================================
1 1 2 1
1 2 1 1

var result = from item in db.Items
group item by new { item.BrandId, item.ModelId, item.TotalPrice }
into gr
select new
{
gr.Key.BrandId,
gr.Key.ModelId,
gr.Key.TotalPrice,
CountA = gr.Count(it => it.StoreId == 1),
CountB = gr.Count(it => it.StoreId == 2),
}

How to merge two lists that share 1 attribute into a third one with LINQ?

I'd wish to create a list of the following class (List):
public class StatusData
{
public DateTime? Date { get; set; }
public int RegisteredUsers { get; set; }
public int Orders { get; set; }
public decimal Import { get; set; }
}
This list should be filled with with information of another 2 lists: a List<Contact> and a List<Purchase>. Both classes have the following shape:
public class Contact
{
public DateTime? RegisterDate { get; set; }
public string Name { get; set; }
}
public class Purchase
{
public DateTime? PurchaseDate { get; set; }
public int PurchaseID {get;set;}
public int Import { get; set; }
}
The idea is that the List should, for every day, which is the amount of Registered users, the amount of purchases and the total import of these purchases. So, in essence, both just share the Date.
However, I can't come with a good LINQ expression to create the List. One solution I considered is to retrieve all the distinct dates among the 2 lists and then iterate over them to retrieve the information I want, but I think this approach is rather "ugly". Is there any way to do what I want to do easily?
EDIT: An example of what I want would be the following:
Contacts
--------
Name RegisteredDate
David 10/10/2013
Paul 09/10/2013
Gina 10/10/2013
Roger 09/10/2013
Rose 05/10/2013
Jean 07/10/2013
Mark 04/10/2013
Lisa 04/10/2013
Purchases
-----------
ID PurchaseDate Import
1 10/10/2013 10
2 10/10/2013 10
3 10/10/2013 20
4 04/10/2013 15
5 04/10/2013 15
6 07/10/2013 20
7 07/10/2013 2
8 07/10/2013 2
Expected result
----------------
Date RegisteredUsers Purchases Import
04/10/2013 2 2 30
05/10/2013 1 0 0
07/10/2013 1 3 24
09/10/2013 2 0 0
10/10/2013 2 3 40
Kind regards

var contacts = new List<Contact>();
var purchases = new List<Purchase>();
var dates = contacts.Select(x => x.RegisterDate.Value)
.Concat(purchases.Select(x => x.PurchaseDate.Value))
.Distinct();
var data = from date in dates
join c in contacts on date equals c.RegisterDate.Value into registered
join p in purchases on date equals p.PurchaseDate.Value into purchased
select new StatusData {
Date = date,
RegisteredUsers = registered.Count(),
Orders = purchases.Count(),
Import = purchases.Sum(x => x.Import)
};
It will return StatusData for all days, when at least one registration OR one purchase was made.

So there are several separate tasks here. The first thing that you're doing is grouping your contacts by the registration date. Next, you're joining that result to the Purchases table based on the date, aggregating count/sums on two different columns. LINQ has a method for each of these two operations:
var query = from contact in contacts
group contact by contact.RegisterDate into contactGroup
join purchase in purchases
on contactGroup.Key equals purchase.PurchaseDate into purchaseGroup
select new StatusData
{
Date = contactGroup.Key,
RegisteredUsers = contactGroup.Count(),
Orders = purchaseGroup.Count(),
Import = purchaseGroup.Sum(p => p.Import),
};

This is really two separate queries with their results merged at the end.
var contact = from c in Contact
group c by c.RegisterDate into c
select new StatusData
{
Date = c.Key,
RegisteredUsers = c.Count(),
Orders = 0,
Import = 0,
};
var purchases = from p in Purchases
group p by p.PurchaseDate into p
select new StatusData
{
Date = p.Key,
RegisteredUsers = 0,
Orders = p.Count(),
Import = p.Sum(x => x.Import),
};
var final = from x in contact.Concat(purchases)
group x by x.Date into x
select new StatusData
{
Date = x.Key,
RegisteredUsers = x.Sum(y => y.RegisteredUsers),
Orders = x.Sum(y => y.Orders),
Import = x.Sum(y => y.Import),
};

How to do a Pivot in Linq [duplicate]

This question already has an answer here:
Closed 10 years ago.
Possible Duplicate:
How can i made a pivot for this
I have a table as provided below
ID | value | Name
--------+---------------+------------------
1 Digital Model
1 companyA Manufacturer
2 Analog Model
2 CompanyB Manufacturer
3 Fiber Model
3 CompanyC Manufacturer
I need to convert this back to
ID | Model | Manufacturer
--------+--------------+-------------------
1 Digital companyA
2 Analog CompanyB
3 Fiber CompanyC
Please help me with the Linq Query for this. Using T-SQL, I am able to convert it properly. However, with Linq I am finding problems writing Query.

Try this:
var results = Data.GroupBy(l => l.Name);
.SelectMany( g =>
new
{
Metadata = g.Key,
data = g
});
var pivoted = new List<PivotedEntity>();
foreach(var item in results)
{
pivoted.Add(
new PivotedEntity
{
Id = item.Id,
Model = item.data.Where(x => x.Name == "Model")
.FirstOrDefault().value,
Manufacturer = item.data.Where(x => x.Name == "Manufacturer")
.FirstOrDefault().value,
});
}
You should first define a new class:
public class PivotedEntity
{
public int Id {get; set;}
public string Model {get; set;}
public string Manufacturer {get; set;}
}

Entity Framework 4.1 count identical database rows

My setup
I have two classes, here shown stripped down to what is needed in this example:
public class Photo : Entity
{
[Key]
public int Id { get; set; }
public virtual ICollection<Tag> Tags { get; set; }
public Photo()
{
Tags = new List<Tag>();
}
}
public class Tag : Entity
{
[Key]
public string Text { get; set; }
public virtual ICollection<Photo> Photos { get; set; }
public Tag()
{
Photos = new List<Photo>();
}
}
As shown above theres is a many-to-many relationship between the two entities.
I'm using EF 4.1 code-first.
Example:
"photo1" has "tag1", "tag2" and "tag3" in its tags navigation property.
"photo2" has "tag2", "tag3" and "tag4" in its tags navigation property.
"photo3" has "tag2" and "tag4" in its tags navigation property.
Total tag count in all photos:
"tag1": 1
"tag2": 3
"tag3": 2
"tag4": 2
Total tags: 8
Note
My end goal is this tag cloud, but using MVC3:
http://www.geekzilla.co.uk/View960C74AE-D01B-428E-BCF3-E57B85D5A308.htm
First question
How do I (using EF) find out how many times the most used tag(s) is used (finding the count of "tag2")?
And the same for the least used tag(s) (count of "tag1" in above example).
In the link above these to lines of code is used:
double.TryParse(tagData.Compute("min(count)", null).ToString(), out min);
double.TryParse(tagData.Compute("max(count)", null).ToString(), out max);
What is the EF/LINQ equivalent?
Second question
How do I get the count for each tag or the count for the 50 most used tags?

Counts by tag:
from t in Context.Tags
select new
{
t.Text,
t.Photos.Count()
}
Most used tag:
(from t in Context.Tags
let photoCount = t.Photos.Count()
orderby photoCount descending
select new
{
t.Text,
photoCount
}).FirstOrDefault()
50 most used tags (may not actually have 50 there):
(from t in Context.Tags
let photoCount = t.Photos.Count()
orderby photoCount descending
select new
{
t.Text,
photoCount
}).Take(50)
Freehand, so might not be 100% syntactically correct or the smallest/most readable way to do it.
Edit: Added Example:
foreach(var result in Context.Tags.Select(x => new { t.Text, t.Photos.Count() }))
{
Console.WriteLine(string.Format("Text: {0}, Count: {1}", result.Text, result.Count.ToString());
}