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Perform a lookup between C# Lists and return matched where value is minimum

I have two lists:
var qtys = new List<InventoryQuantity>()
{
new InventoryQuantity() { WarehouseId = 1, QuantityInWarehouse = 0 },
new InventoryQuantity() { WarehouseId = 2, QuantityInWarehouse = 452 },
new InventoryQuantity() { WarehouseId = 3, QuantityInWarehouse = 184 },
new InventoryQuantity() { WarehouseId = 4, QuantityInWarehouse = 328 },
new InventoryQuantity() { WarehouseId = 5, QuantityInWarehouse = 0 },
};
var times = new List<WarehouseTransitTime>()
{
new WarehouseTransitTime() { WarehouseId = 1, TransitDays = 1 },
new WarehouseTransitTime() { WarehouseId = 2, TransitDays = 4 },
new WarehouseTransitTime() { WarehouseId = 3, TransitDays = 2 },
new WarehouseTransitTime() { WarehouseId = 4, TransitDays = 3 },
new WarehouseTransitTime() { WarehouseId = 5, TransitDays = 5 },
};
class InventoryQuantity
{
public int WarehouseId { get; set; }
public int QuantityInWarehouse { get; set; }
}
class WarehouseTransitTime
{
public int WarehouseId { get; set; }
public int TransitDays { get; set; }
}
I need to return the WarehouseId from qtys where the Quantity > 0 and the WarehouseId equals the minimum transit days WarehouseId in times.
I know I can do something like below but seems clunky and there must be an elegant solution.
public int NearestWarehouse()
{
var withQty = qtys.Where(i => i.QuantityInWarehouse > 0);
var orderedTransit = times.OrderBy(tt => tt.TransitDays).ToList();
//loop and compare
}
Example data:
qtys
WarehouseId | Quantity
1 | 0
2 | 452
3 | 184
4 | 328
5 | 0
times
WarehouseId | TransitTime
1 | 1
2 | 4
3 | 2
4 | 3
5 | 5
Expected output would be 3, because warehouse 3 has inventory and the shortest transit time (2)

It seems to me that the cleanest and simplest query is this:
var query =
from q in qtys
where q.QuantityInWarehouse > 0
join t in times on q.WarehouseId equals t.WarehouseId
orderby t.TransitDays
select q.WarehouseId;
var warehouseId = query.FirstOrDefault();
This gives me 3.

What you want is a group join:
Functional Syntax
var query1 = qtys.Where(q => q.QuantityInWarehouse > 0)
.GroupJoin(times, q => q.WarehouseId, t => t.WarehouseId, (q, t) => new { q.WarehouseId, TransitDays = t.DefaultIfEmpty().Min(grp => grp?.TransitDays) })
.OrderBy(g => g.TransitDays)
.FirstOrDefault();
Query Syntax
var query2 = from q in qtys
join t in times on q.WarehouseId equals t.WarehouseId into grp
where q.QuantityInWarehouse > 0
select new
{
q.WarehouseId,
TransitDays = grp.DefaultIfEmpty().Min(g => g?.TransitDays)
};
var result = query2.OrderBy(g => g.TransitDays)
.FirstOrDefault();
A group join will join two lists together on their corresponding keys--similar to a database join--and the associated values to those keys will be grouped into an enumerable. From that enumerable, you can derive the minimum value that you care about, TransitDays in this case.
There is no equivalent to "first or default" in query syntax. The easiest approach is just to apply the same OrderBy and FirstOrDefault against the query variable, as demonstrated above.

Well you mention an AND relation between the two, right?
I was thinking of databases with a forignkey... but Linq prety much does it if your lists aren't to big:
keys = qtys.Where(i => i.QuantityInWarehouse > 0).Select(i => i.WarehouseId).ToList();
// get the smallest not a list
var result = times.Where(tt => keys.Contains(tt.wharehouseId)).orderby(tt => tt.Transitdays).FirstOrDefault();
Otherwise you could have Dictionary with ID as key...

You can do it like this..
var withQty = (from q in qtys
join t in times on q.WarehouseId equals t.WarehouseId
where q.QuantityInWarehouse > 0
select new { q.WarehouseId, t.TransitDays })
.OrderBy(item => item.TransitDays).FirstOrDefault();
return withQty?.WarehouseId ?? 0;

Linq query - List within List [duplicate]

This question already has answers here:
Group by in LINQ
(11 answers)
Closed 5 years ago.
I'm trying to select a list that contains Fund.Name and List<Investment>.
var funds = new List<Fund>
{
new Fund { Id = 1 , Name = "good" },
new Fund { Id = 2, Name = "bad" }
};
var investments = new List<Investment>
{
new Investment { Fund = funds[0], Value = 100 },
new Investment { Fund = funds[0], Value = 200 },
new Investment { Fund = funds[1], Value = 300 }
};
Then I'm trying to create the query with this:
var query = from f in funds
join i in investments
on f.Id equals i.Fund.Id
select new { f.Name, i };
I wanted something like this:
{ Name = good, {{ Id = 1, Value = 100 }, { Id = 1, Value = 200 }}},
{ Name = bad, { Id = 2, Value = 300 }}
But I'm getting something like this:
{ Name = good, { Id = 1, Value = 100 }},
{ Name = good, { Id = 1, Value = 200 }},
{ Name = bad, { Id = 2, Value = 300 }}

Try using GroupJoin.
var query = funds.GroupJoin(investments, f => f.Id, i => i.Fund.Id, (f, result) => new { f.Name, result });

Convert Objects into Hierarchy based on Number Sequence

I have following data Structure and i want to put covert it in a Hierarchy based on RelationId. This is sorted on RelationId.
Id = 2 has relationId =2 and following two rows has realtionId =0 . That represent the Id=3 and Id=4 are child of Id = 2
Id Name RelationId SortOrder
1 A 1 1
2 B 2 2
3 C 0 3
4 D 0 4
5 E 3 5
6 F 0 6
7 G 0 7
8 H 4 8
End Result would be like following
Id = 1
|
Id = 2
|___ Id = 3 , Id = 4
Id = 5
|___ Id= 6 , Id=7
Id = 8
The desired result is as following (for simplicity representing it as List). This would be a List<Something> in C#
Result =
[
{ Id = 1, Name = A, Children = Null },
{ Id = 2, Name = B, Children = [{ Id = 3, Name = C }, {Id = 4, Name = D }] },
{ Id = 5, Name = E, Children = [{ Id = 6, Name = F }, {Id = 7, Name = G }] },
{ Id = 8, Name = H}
]
My unsuccessful attempt is as following
var finalResult = new List<sampleDataClass>();
var sampleData = GetMeSampleData();
var count = sampleData.Count();
foreach (var item in sampleData)
{
var alreadyExist = finalResult.Any(x => x.Id == item.Id);
var newObject = new sampleDataClass();
if (!alreadyExist && item.RelationId!= 0)
{
newObject = item;
}
for (int i = item.SortOrder; i < count; i++)
{
if (sampleData[i].RelationId== 0)
{
newObject.Children.Add(sampleData[i]);
}
}
finalResult.Add(newObject );
}

Since your RelationId decides whether it is a root or nested element, you could form a group based on these relation and do this. I would suggest using Linq
List<SomeData> somedata = ... // your data.
int index=0;
var results = somedata
.Select(x=> new {gid = x.RelationId ==0? index: ++index, item=x})
.GroupBy(x=> x.gid)
.Select(x=> {
var first = x.FirstOrDefault();
return new
{
Id = first.item.Id,
Name = first.item.Name,
Children = x.Skip(1).Select(s=> new {
Id = s.item.Id,
Name = s.item.Name,
})
};
})
.ToList();
Output :
Id=1, Name=A
Id=2, Name=B
Id=3, Name=C
Id=4, Name=D
Id=5, Name=E
Id=6, Name=F
Id=7, Name=G
Id=8, Name=H
Check this Working Code

I have done it like this. Don't know if there can be some more elegant solution
var data = new List<MyDataObject>();
var SampleData = GetMeSampleData;
var count = SampleData.Count();
for (int i=0;i<count;i++)
{
var rootAdded = false;
var relationId = SampleData[i].relationId;
var alreadyExist = data.Any(x => x.Id == SampleData[i].Id);
var mydataObject = new MyDataObject();
if (!alreadyExist && SampleData[i].RelationId != 0)
{
mydataObject = SampleData[i];
rootAdded = true;
}
for(int j=i+1;j<count;j++)
{
if ((SampleData[j].RelationId == 0 && rootAdded))
{
mydataObject.Children.Add(SampleData[j]);
}
if (SampleData[j].SubjectId != 0)
break;
}
if (rootAdded)
{
data.Add(mydataObject);
}

Code to collapse duplicate and semi-duplicate records?

I have a list of models of this type:
public class TourDude {
public int Id { get; set; }
public string Name { get; set; }
}
And here is my list:
public IEnumerable<TourDude> GetAllGuides {
get {
List<TourDude> guides = new List<TourDude>();
guides.Add(new TourDude() { Name = "Dave Et", Id = 1 });
guides.Add(new TourDude() { Name = "Dave Eton", Id = 1 });
guides.Add(new TourDude() { Name = "Dave EtZ5", Id = 1 });
guides.Add(new TourDude() { Name = "Danial Maze A", Id = 2 });
guides.Add(new TourDude() { Name = "Danial Maze B", Id = 2 });
guides.Add(new TourDude() { Name = "Danial", Id = 3 });
return guides;
}
}
I want to retrieve these records:
{ Name = "Dave Et", Id = 1 }
{ Name = "Danial Maze", Id = 2 }
{ Name = "Danial", Id = 3 }
The goal mainly to collapse duplicates and near duplicates (confirmable by the ID), taking the shortest possible value (when compared) as name.
Where do I start? Is there a complete LINQ that will do this for me? Do I need to code up an equality comparer?
Edit 1:
var result = from x in GetAllGuides
group x.Name by x.Id into g
select new TourDude {
Test = Exts.LongestCommonPrefix(g),
Id = g.Key,
};
IEnumerable<IEnumerable<char>> test = result.First().Test;
string str = test.First().ToString();

If you want to group the items by Id and then find the longest common prefix of the Names within each group, then you can do so as follows:
var result = from x in guides
group x.Name by x.Id into g
select new TourDude
{
Name = LongestCommonPrefix(g),
Id = g.Key,
};
using the algorithm for finding the longest common prefix from here.
Result:
{ Name = "Dave Et", Id = 1 }
{ Name = "Danial Maze ", Id = 2 }
{ Name = "Danial", Id = 3 }
static string LongestCommonPrefix(IEnumerable<string> xs)
{
return new string(xs
.Transpose()
.TakeWhile(s => s.All(d => d == s.First()))
.Select(s => s.First())
.ToArray());
}

I was able to achieve this by grouping the records on the ID then selecting the first record from each group ordered by the Name length:
var result = GetAllGuides.GroupBy(td => td.Id)
.Select(g => g.OrderBy(td => td.Name.Length).First());
foreach (var dude in result)
{
Console.WriteLine("{{Name = {0}, Id = {1}}}", dude.Name, dude.Id);
}

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());
}
}
}