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Linq query and potential self join/group by

Suffering sadly from brain fade. I have the following scenario:
void Main()
{
List<CaseBase> caseList = new List<UserQuery.CaseBase>();
caseList.Add(new CaseBase() {CaseID = 1, CaseSequence = 1, CaseStatus = 1});
caseList.Add(new CaseBase() {CaseID = 1, CaseSequence = 2, CaseStatus = 2});
caseList.Add(new CaseBase() {CaseID = 2, CaseSequence = 1, CaseStatus = 1});
var cases = caseList.Where(x => new List<int> {2}.Contains(x.CaseStatus));
}
// Define other methods and classes here
public class CaseBase
{
public int CaseID {get;set;}
public int CaseSequence {get;set;}
public int CaseStatus {get;set;}
}
Which returns the expected
CaseID
CaseSequence
CaseStatus
1
2
2
What I want are all cases with the same ID where one of them has a status of 2.
CaseID
CaseSequence
CaseStatus
1
1
1
1
2
2
Which should be simple but I'm struggling for a simple solution.

There are a couple of ways to proceed:
You can combine the cases by CaseID and select the matching groups and then break them apart:
var cases = caseList
.GroupBy(c => c.CaseID)
.Where(cg => cg.Any(c => new List<int> { 2 }.Contains(c.CaseStatus)))
.SelectMany(cg => cg);
You can find the desired CaseIDs and then get all matching cases:
var wantedCaseIDs = caseList
.Where(c => new List<int> { 2 }.Contains(c.CaseStatus))
.Select(c => c.CaseID)
.ToHashSet();
var cases = caseList.Where(c => wantedCaseIDs.Contains(c.CaseID));

Or you might want to do it like this:
void Main()
{
List<CaseBase> caseList = new List<UserQuery.CaseBase>();
caseList.Add(new CaseBase() { CaseID = 1, CaseSequence = 1, CaseStatus = 1 });
caseList.Add(new CaseBase() { CaseID = 1, CaseSequence = 2, CaseStatus = 2 });
caseList.Add(new CaseBase() { CaseID = 2, CaseSequence = 1, CaseStatus = 1 });
var cases = caseList.Where(x => new List<int> { 2 }.Contains(x.CaseStatus))
.Join(caseList,x => x.CaseID,y => y.CaseID,(x,y) => new {x,y})
.Select(z => z.y)
.Dump();
}

Linq how to find max repeat items?

I have a list of object (ProductInfo).
ProductInfo contains an id, name, and an option.
Imagine this sample, i have this
ProductInfo Id => 1, Name => XXX, Option = A
ProductInfo Id => 1, Name => XXX, Option = B
ProductInfo Id => 2, Name => DEB, Option = A
ProductInfo Id => 2, Name => DEB, Option = B
ProductInfo Id => 2, Name => DEB, Option = C
ProductInfo Id => 3, Name => ZZZ, Option = D
....
....
We see we have 2 time the option A AND B for product 1 and 2.
My goal will be to obtain the max repeat item for each product in the list.
i would like to obtain as result this :
Id = 1, Name = XXX = A, count = 2
Id =2, Name = DEB, count = 2
How i can do that ?
thanks for your time

try to do this code:
var list = new List<ProductInfo> {
new ProductInfo { Id = 1, Name = "XXX", Option = "A"},
new ProductInfo { Id = 1, Name = "XXX", Option = "B" },
new ProductInfo { Id = 2, Name = "DEB", Option = "A" },
new ProductInfo { Id = 2, Name = "DEB", Option = "B"},
new ProductInfo { Id = 2, Name = "DEB", Option = "C" },
new ProductInfo { Id = 3, Name = "ZZZ", Option = "D" }
};
var x = from p in list
group p by new { p.Id, p.Name, p.Option } into g
select new
{
Id = g.Key.Id,
Name = g.Key.Name,
Count = list.Count(m => m.Name == g.Key.Name)
};
var t = x.Distinct();

You can use GroupBy on the Name and Id parameter. Sorry read that wrong at first.

Find the product with the lowest price return with name LINQ

I´m new to LINQ and I´m trying to find the lowest price in a list and return the name of it.
I´ve been searching and haven´t find anything that I can use.
The List is in a class Category but I have to write out the result in main.
It´s a C# in a Microsoft Visual Studio.
The list I have to find the lowest price from is like this:
public static IEnumerable<Product> GetProducts( )
{
List<Product> products = new List<Product>( );
products.Add( new Product { Name = "Milk", Price = 90, CategoryID = 4, ID = 1 } );
products.Add( new Product { Name = "Cheese", Price = 130, CategoryID = 4, ID = 2 } );
products.Add( new Product { Name = "Butter", Price = 110, CategoryID = 4, ID = 3 } );
products.Add( new Product { Name = "Apple juice", Price = 230, CategoryID = 1, ID = 4 } );
products.Add( new Product { Name = "Grape juice", Price = 240, CategoryID = 1, ID = 5 } );
products.Add( new Product { Name = "Beetroot juice", Price = 300, CategoryID = 1, ID = 6 } );
products.Add( new Product { Name = "Carrot juice", Price = 190, CategoryID = 1, ID = 7 } );
products.Add( new Product { Name = "Ginger ale", Price = 990, CategoryID = 1, ID = 8 } );
products.Add( new Product { Name = "Oregano", Price = 500, CategoryID = 2, ID = 9 } );
products.Add( new Product { Name = "Salt", Price = 550, CategoryID = 2, ID = 10 } );
products.Add( new Product { Name = "Pepper", Price = 490, CategoryID = 2, ID = 11 } );
products.Add( new Product { Name = "Carrots", Price = 300, CategoryID = 3, ID = 12 } );
products.Add( new Product { Name = "Spinach", Price = 250, CategoryID = 3, ID = 13 } );
products.Add( new Product { Name = "Onion", Price = 200, CategoryID = 3, ID = 14 } );
products.Add( new Product { Name = "Garlic", Price = 150, CategoryID = 3, ID = 15 } );
products.Add( new Product { Name = "Tomatoes", Price = 100, CategoryID = 3, ID = 16 } );
return products;
}

from p in Products where p.Price == Products.Min(x=>x.Price) select p.Name
The problem with taking the First from an Ordered list is that it doesn't deal with the possibilities of multiple items having the same lowest price.

products.OrderBy(p => p.Price).Select(p => p.Name).First();
or
products.OrderBy(p => p.Price).First().Name;

This returns Milk
string namesOfProductWithLowestPrice = products
.GroupBy(p => p.Price)
.OrderBy(g => g.Key)
.Select(g => string.Join(",", g.Select(p => p.Name)))
.FirstOrDefault();
In case of multiple products with the lowest price it will concatenate the names with comma.

EDIT I've changed the answer after Tim Schmelters comment on Ralph Shillingtons answer, which is very similiar to mine, but in a different syntax.
int lowestPrice = from prod in GetProducts()
select prod.Price).Min();
var lowestPriceProduct = from p in GetProducts()
where lowestPrice == p.Price)
select p;

EF LINQ query where meet all list or array

i have these data:
class MyTableItem
{
public long id { get; set; }
public long listId { get; set; }
public long listFieldValue { get; set; }
public long parentId { get; set; }
}
and:
var myData = new MyTableItem[]
{
new MyTableItem { id = 1, listId = 1, listFieldValue = 100, parentId = 1 },
new MyTableItem { id = 2, listId = 2, listFieldValue = 130, parentId = 1 },
new MyTableItem { id = 3, listId = 3, listFieldValue = 170, parentId = 1 },
new MyTableItem { id = 4, listId = 4, listFieldValue = 170, parentId = 1 },
new MyTableItem { id = 5, listId = 1, listFieldValue = 100, parentId = 2 },
new MyTableItem { id = 6, listId = 2, listFieldValue = 130, parentId = 2 },
new MyTableItem { id = 7, listId = 3, listFieldValue = 170, parentId = 2 },
new MyTableItem { id = 8, listId = 4, listFieldValue = 270, parentId = 2 },
...(continue)
};
var myMatchConditions = new int?[][] //id, rangeTypeId(equal, more, less, between), from, to
{
new int?[] { 1, 1, 100, null },
new int?[] { 2, 2, 125, null },
new int?[] { 3, 3, null, 175 },
new int?[] { 4, 4, 130, 180 }
...(can continue more)
};
now i need to know which myData (groupBy parrentId) are matched by my conditions,
let me explain more:
I want to know which parrent Id has listFieldValue where:
1) (listId == 1)&&(listFieldValue == 100)
and
2) (listId == 2)&&(listFieldValue > 125)
and
3) (listId == 3)&&(listFieldValue < 175)
and
4) ((listId == 4)&&(listFieldValue > 130)&&(listFieldValue < 180))
it must return (1)parrentId.

There you go. Explanations are at the bottom:
IEnumurable<MyTableItem> temp = myData ;
for (int i = 0; i < myMatchConditions.GetLength(0); i++)
{
var conditionType = myMatchConditions[i,1];
if (conditionType == 1)
{
temp = temp.Where(_ => _listFieldValue == myMatchConditions[i,2]);
}
else
{
if (conditionType == 2 || conditionType == 4)
{
temp = temp.Where(_ => _listFieldValue > myMatchConditions[i,2]);
}
if (conditionType == 3 || conditionType == 4)
{
temp = temp.Where(_ => _listFieldValue < myMatchConditions[i,3]);
}
}
}
I'm using IEnumurable<MyTableItem> which means it's Linq and not Linq to entities. I chose that because your myData is not an EF table but a simple array.
I go through all the "rows" with a for, you can do that with a foreach, and I add the Where clauses to filter out more and more each time (The actual filtering will happen only when you use that temp list)
I add a condition based on the type in the second cell, and if the type is 4... I add both the 2 and 3 type rules... which makes a 4 type rule

What is the easiest way to fixed pivot transform this data in C# (linq?)?

Given this example data (in .NET classes where Po, Sku, Qty are properties):
PO, Sku, Qty
1,ABC,1
1,DEF,2
1,GHI,1
1,QWE,1
1,ASD,1
1,ZXC,5
1,ERT,1
2,QWE,1
2,ASD,11
2,ZXC,1
3,ERT,1
3,DFG,1
3,DFH,1
3,CVB,4
3,VBN,1
3,NMY,1
I need to transform it into a fixed column format, with a max of 5 SKUs per line (repeating the PO if needed for > 5):
PO, SkuA, QtyA, SkuB, QtyB, SkuC, QtyC, SkuD, QtyD, SkuE, QtyE
1, ABC, 1, DEF, 2, GHI, 1, QWE, 1, ASD, 1
1, ZXC, 5, ERT, 1, , , , , ,
2, QWE, 1, ASD, 11, ZXC, 1, , , ,
3, ERT, 1, DFG, 1, DFH, 1, CVB, 4, VBN, 1
3, NMY, 1, , , , , , , ,
Output can be CSV (which is what I'm outputting), or .NET classes - no matter there. Is there a simple way to do this in Linq by grouping by PO, then by counts of 5?
EDIT: I have no control of over the destination format. And for anyone interested, it's VendorNet and VendorBridge that require this nonsense.

Firstly, here's the query that will generate the correct hierarchy of objects. I'm using anonymous types but it's easy enough to change it to use your own proper classes.
var query = yourData
.GroupBy
(
x => x.PO
)
.SelectMany
(
x => x.Select
(
(y, i) => new { y.PO, y.Sku, y.Qty, Key = i / 5 }
)
)
.GroupBy
(
x => new { x.PO, x.Key }
);
Using LINQ to create the CSV from the query results is bit of a hack, but it gets the job done. (The "benefit" of using LINQ is that you could chain the original query and the CSV generation into a single, massive statement, should you wish.)
IEnumerable<string> csvLines = query
.Select
(
x => x.Aggregate
(
new { Count = 0, SB = new StringBuilder() },
(a, y) => new
{
Count = a.Count + 1,
SB = ((a.SB.Length == 0) ? a.SB.Append(y.PO) : a.SB)
.Append(", ").Append(y.Sku).Append(", ").Append(y.Qty)
},
a => a.SB.ToString() + string.Join(", , ", new string[6 - a.Count])
)
);
string csv = string.Join(Environment.NewLine, csvLines.ToArray());
In my opinion, creating the CSV without using LINQ makes the code much more readable:
StringBuilder sb = new StringBuilder();
foreach (var group in query)
{
int count = 0;
foreach (var item in group)
{
if (count++ == 0)
{
sb.Append(item.PO);
}
sb.Append(", ").Append(item.Sku).Append(", ").Append(item.Qty);
}
while (count++ < 5)
{
sb.Append(", , ");
}
sb.Append(Environment.NewLine);
}
string csv = sb.ToString();

Here you go. I didn't format the output the way you wanted. But this should give you an idea of how to pivot rows. Hope this helps :-)
public class MyClass
{
public int PO { get; set; }
public String SKU { get; set; }
public int Qty { get; set; }
public static IEnumerable<MyClass> GetList()
{
return new List<MyClass>()
{
new MyClass {PO = 1, SKU = "ABC", Qty = 1},
new MyClass {PO = 1, SKU = "DEF", Qty = 2},
new MyClass {PO = 1, SKU = "GHI", Qty = 1},
new MyClass {PO = 1, SKU = "QWE", Qty = 1},
new MyClass {PO = 1, SKU = "ASD", Qty = 1},
new MyClass {PO = 1, SKU = "ZXC", Qty = 5},
new MyClass {PO = 1, SKU = "ERT", Qty = 1},
new MyClass {PO = 2, SKU = "QWE", Qty = 1},
new MyClass {PO = 2, SKU = "ASD", Qty = 1},
new MyClass {PO = 2, SKU = "ZXC", Qty = 5},
};
}
}
EDIT: I've fixed the query based on Luke's comment
var lQuery =
MyClass.GetList()
.GroupBy(pArg => pArg.PO)
.Select(pArg => new
{
Test = pArg.Select((pArg1, pId) =>
new {ID = (pId / 5),
pArg1.PO, pArg1.SKU, pArg1.Qty})
.GroupBy(pArg1 => pArg1.ID)
.Select(pArg1 =>
pArg1.Aggregate(pArg.Key.ToString(),
(pSeed, pCur) =>
pSeed + pCur.SKU + ","))
});