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Grouping and summing by Linq

I would like to get the total order amount for each customer with Linq, I know I need to group and sum I have only succeeded to group without summing the whole amount for each order.
var OrderByCustumer = new[] {
new { name = "cust1", order = 400 },
new { name = "cust1", order = 250 },
new { name = "cust1", order = 130 },
new { name = "cust2", order = 30 },
new { name = "cust3", order = 205}
};
var res= OrderByCustumer.GroupBy(x=>x.name).Select((x,y)=>new{
a=x.Key
});
foreach(var a in res){
Console.WriteLine(a);
}
.**
OutPut
a = cust1
a = cust2
a = cust3
**

Try this
var res = OrderByCustumer.GroupBy(x => x.name).Select(x => new {
a = x.Key,
sum = x.Sum(c => c.order)
});
foreach (var item in res)
{
Console.WriteLine($"{ item.a} - Sum = {item.sum}");
}

How to merge group by list and sum no-key value

For example i have a grouped by list:
List<Cl> list = new List<Cl>()
{
new Cl() { vi = 1, vs = "q", am = 20 },
new Cl() { vi = 1, vs = "w", am = 30 },
new Cl() { vi = 2, vs = "w", am = 40 },
new Cl() { vi = 1, vs = "q", am = 50 }
};
groups = list.GroupBy(b => new { b.vi, b.vs }).ToList();
And i want to get merged list with summing am field:
Key am
[1, "q"] [70]
[1, "w"] [30]
[2, "w"] [40]
Is it possible to realize it without Dictionaries or KeyValuePair?
I will be grateful for any help.

First GroupBy(), then Sum() up the am values of each group
List<Cl> groups = list.GroupBy(b => new { b.vi, b.vs })
.Select(x => new Cl() { vi = x.Key.vi,
vs = x.Key.vs,
am = x.Sum(y => y.am) }).ToList();

You could try something like this:
class Key
{
public int Vi { get; set; }
public string Vs { get; set; }
public Key(int vi, string vs)
{
Vi = vi;
Vs = vs;
}
}
var result = groups = list.GroupBy(b => new { b.vi, b.vs })
.Select(gr=> new { Key = Key(gr.vi,gr.vs)
, Value = gr.Sum(x=>x.am)})
.ToList();

Try it like this:
var groups = list.GroupBy(b => new { b.vi, b.vs })
.Select(g => new { g.Key, am = g.Sum(s => s.am)})
.ToList();

comparison of the list in the list

I have a list of lists:
List<Product> productList = new List<Product>()
{
new Product()
{
Id = 1,
Model = "Phone",
TypeProd = new CheckTypes
{
ChTypes = new List<CHType>
{
new CHType
{
Id = 8,
IdName = "261"
},
new CHType
{
Id = 9 ,
IdName = "149"
}
}
}
},
new Product
{
Id = 1,
Model = "Printer",
TypeProd = new CheckTypes
{
ChTypes = new List<CHType>
{
new CHType
{
Id = 8,
IdName = null
},
new CHType
{
Id = 8,
IdName = "261"
}
}
}
}
};
And I want to get the first item of this list by comparing the IdName elements with a string[]:
string[] arrStr = new string[] { "261", "149" };
How can I do this better? Tried using foreach and by creating a temporary object that takes an array value and then uses intersect to compare.

You could do it pretty simply with LINQ:
var product = productList
.FindAll(x => x.TypeProd.ChTypes
.All(y => arrString.Contains(y.IdName));
This will give you all products whose TypeProd.ChTypes elements are all in arrString.
For faster performance, you may want to turn arrString into a HashSet<string>.

Select top N records after filtering in each group

I am an old bee in .NET but very new to Linq! After some basic reading I have decided to check my skill and I failed completely! I don't know where I am making mistake.
I want to select highest 2 order for each person for while Amount % 100 == 0.
Here is my code.
var crecords = new[] {
new {
Name = "XYZ",
Orders = new[]
{
new { OrderId = 1, Amount = 340 },
new { OrderId = 2, Amount = 100 },
new { OrderId = 3, Amount = 200 }
}
},
new {
Name = "ABC",
Orders = new[]
{
new { OrderId = 11, Amount = 900 },
new { OrderId = 12, Amount = 800 },
new { OrderId = 13, Amount = 700 }
}
}
};
var result = crecords
.OrderBy(record => record.Name)
.ForEach
(
person => person.Orders
.Where(order => order.Amount % 100 == 0)
.OrderByDescending(t => t.Amount)
.Take(2)
);
foreach (var record in result)
{
Console.WriteLine(record.Name);
foreach (var order in record.Orders)
{
Console.WriteLine("-->" + order.Amount.ToString());
}
}
Can anyone focus and tell me what would be correct query?
Thanks in advance

Try this query:
var result = crecords.Select(person =>
new
{
Name = person.Name,
Orders = person.Orders.Where(order => order.Amount%100 == 0)
.OrderByDescending(x => x.Amount)
.Take(2)
});
Using your foreach loop to print the resulting IEnumerable, the output of it is:
XYZ
-->200
-->100
ABC
-->900
-->800

This has already been answered but if you didn't want to create new objects and simply modify your existing crecords, the code would look like this alternatively. But you wouldn't be able to use anonymous structures like shown in your example. Meaning you would have to create People and Order classes
private class People
{
public string Name;
public IEnumerable<Order> Orders;
}
private class Order
{
public int OrderId;
public int Amount;
}
public void PrintPeople()
{
IEnumerable<People> crecords = new[] {
new People{
Name = "XYZ",
Orders = new Order[]
{
new Order{ OrderId = 1, Amount = 340 },
new Order{ OrderId = 2, Amount = 100 },
new Order{ OrderId = 3, Amount = 200 }
}
},
new People{
Name = "ABC",
Orders = new Order[]
{
new Order{ OrderId = 11, Amount = 900 },
new Order{ OrderId = 12, Amount = 800 },
new Order{ OrderId = 13, Amount = 700 }
}
}
};
crecords = crecords.OrderBy(record => record.Name);
crecords.ToList().ForEach(
person =>
{
person.Orders = person.Orders
.Where(order => order.Amount%100 == 0)
.OrderByDescending(t => t.Amount)
.Take(2);
}
);
foreach (People record in crecords)
{
Console.WriteLine(record.Name);
foreach (var order in record.Orders)
{
Console.WriteLine("-->" + order.Amount.ToString());
}
}
}

Multiple group by and Sum LINQ

I have a products sales table that looks like this:
saleDate prod qty
10/22/09 soap 10
09/22/09 pills 05
09/25/09 soap 06
09/25/09 pills 15
I need to make the SUM of each MONTH so the final table would look like this:
saleDate prod qty
10/09 soap 10
09/09 soap 06
09/09 pills 20
Can I do this with LINQ?

var products = new[] {
new {SaleDate = new DateTime(2009,10,22), Product = "Soap", Quantity = 10},
new {SaleDate = new DateTime(2009,09,22), Product = "Pills", Quantity = 5},
new {SaleDate = new DateTime(2009,09,25), Product = "Soap", Quantity = 6},
new {SaleDate = new DateTime(2009,09,25), Product = "Pills", Quantity = 15}
};
var summary = from p in products
let k = new
{
//try this if you need a date field
// p.SaleDate.Date.AddDays(-1 *p.SaleDate.Day - 1)
Month = p.SaleDate.ToString("MM/yy"),
Product = p.Product
}
group p by k into t
select new
{
Month = t.Key.Month,
Product = t.Key.Product,
Qty = t.Sum(p => p.Quantity)
};
foreach (var item in summary)
Console.WriteLine(item);
//{ Month = 10/09, Product = Soap, Qty = 10 }
//{ Month = 09/09, Product = Pills, Qty = 20 }
//{ Month = 09/09, Product = Soap, Qty = 6 }

var q = from s in sales
group s by new {saleDate = s.saleDate.ToString("MM/yy"), s.prod} into g
select new { g.Key.saleDate, g.Key.prod, qty = g.Sum(s => s.qty) };

class Program
{
static void Main(string[] args)
{
var sales = new List<Sale>();
sales.Add(new Sale() { Product = "soap", saleDate = new DateTime(2009, 10, 22), Quantity = 10});
sales.Add(new Sale() { Product = "soap", saleDate = new DateTime(2009, 9,22), Quantity = 6});
sales.Add(new Sale() { Product = "pills", saleDate = new DateTime(2009,9,25), Quantity = 15});
sales.Add(new Sale() { Product = "pills", saleDate = new DateTime(2009,9,25), Quantity = 5});
var q = from s in sales
group s by new { s.Product, s.saleDate.Month, s.saleDate.Year } into g
select new {Month = String.Format("{0:MM/yy}", new DateTime(g.Key.Year, g.Key.Month, 1)), product = g.Key.Product, quantity = g.Sum(o=>o.Quantity)};
}
}
class Sale
{
public DateTime saleDate { get; set; }
public int Quantity { get; set; }
public string Product { get; set; }
}

Sure.
It'll look like this:
var GroupedSales =
from p in products
group p by p.saleDate.Month into g
select new { saleMonth = g.saleDate.Month, QtySold = g.Sum(p => p.qty) };
See: http://msdn.microsoft.com/en-us/vcsharp/aa336747.aspx#sumGrouped
Also, note that I was operating under the assumption that your dataset only had 2009 data. If you want to group by month/year, you can use saleDate.ToString("yyyyMM") instead of saleDate.Month.