.net - Use LINQ To Count The Number Of Combinations Existing In Two Lists?
Jun 17, 2010
I'm trying to create a LINQ query (or queries) that count the total number of occurences of a combinations of items in one list that exist in a different list. For example, take the following lists:
CartItems DiscountItems
========= =============
AAA AAA
[code]....
The result of the query operation should be 2 since I can find two combinations of AAA and BBB (from DiscountItems) within the contents of CartItems.My thinking in approaching the query is to join the lists together to shorten CartItems to only include items from DiscountItems. The solution would be to find the CartItem in the resulting query that occurs the least amount of times, thus indicating how many combinations of items exist in CartItems.When CartItems is filtered to only the items in DiscountItems, it can be visually displayed like this:
CartItems that get a discount
=============================
AAA BBB <= This combination is eligible for a discount
AAA BBB <= This combination is eligible for a discount
AAA <= Not eligible
Thus, because there are 2 combinations of the discount in the Cart, the result is 2.Here's the query I already have, but it's not working. query results in an enumeration with 100 items, far more than I expected.
Dim query = From cartItem In Cart.CartItems
Group Join discountItem
In DiscountGroup.DiscountItems
[code]....
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Jun 28, 2010
This question is very similar to a previous question of mine, Use LINQ to count the number of combinations existing in two lists, except with some further twists.
I have a list of CartItems that can receive a discount based on the items specified in the list of DiscountItems. I need to be able to pull out the items in the Cart that can receive a discount and apply the appropriate discount specfied in the DiscountItem. The discount is only applied for each combination that exists. Here's what the two lists might look like to before the discount is applied[code]...
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Oct 28, 2009
I want simply to generate rapidly combinations of 16 take by2 using linq.So I want to display me the combinations only not arrangements:1,2 (not 2,1 because there are combinations)...1,16 2,3 (not 3,2) because they are combinations..2,16..Comb of 16 take by 2 makes 120 so 120 combinations will be displayed on screen.[code]So my question is how to display rapidly on screen the combinations of 16 take by 2 using this Enumerable class of Visual Basic .NET(the 120combinations in fact)
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Jun 17, 2012
I'm using vb.net. Basically, I have a drop down list, text box and a submit button. You choose a movie director from a drop down list, then type in a movie, click button and it adds the data to my database.There's another button which hides/shows drop down list, text box and submit button using Visible = True and Visible = False, but what I don't like about it is when it hides the things I said before, it leaves some white/empty space like if they are still there, but not visible.Is there anyway to put some kind of holder/container and place a button which when clicked could add my drop down list, text box and submit buttons to that place?
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Dec 10, 2010
designing a Windows based computer program that will allow a user to enter some number (n) and a choice of a count up or count down for that many numbers. So for example, the user enters 5 as their number and selects the count down option, the message box displayed would contain the message: "Here are your numbers: 5,4,3,2,1,0"
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Oct 1, 2011
This is what I have, but It doesn't work with strings for some reason (only text files):
[Code]...
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Jun 9, 2011
I have two Lists of custom objects:
List1: Year, Month, ValueA
List2: Year, Month, ValueB
I want to get a third List with a merge between the two:
List3: Year, Month, ValueA, ValueB
Is there any elegant way to perform that in LINQ VB.Net?
Example:
List1:
2010 - 6 - 2
2010 - 7 - 5
[Code].....
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Jul 4, 2011
Suppose that I have more than one List (L1,L2,L3,L4) of instances of a class [code]Now I want to querry the 4 lists with one call like Dim L= (from P as MyClass in (L1,L2,L3,L4) where p.Datetime> XXXXX order by p.datetime select p).tolist..is it possible to do something like that? I Know that I could do a FOR NEXT loop with each list but i am looking for a way to do this with a single call
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Mar 15, 2012
I have collections of 2 different types - let's call them Cars and Trucks. Both share base class Vehicle, which has property Passengers.I want to merge them into a single collection ordered by that property. E.g., merge Cars and Trucks and order by Passengers.
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Sep 19, 2010
I accept both C# and VB.NET suggestion, even though I'm writing an app in VB.NET I have two lists of intergers
List1 {1,2,3,5}
List2 {2,4,6,7}
I want to have new List3 {4,6,7} which is composed of elements of List2 that are not in List1. I know I can write a nice For Each loop for this but I want it done in LINQ I've been looking for such methods at Enumerable Methods, but I can't find it.
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Jan 8, 2012
how do i count the number of rows that are affected when I updated a table, and display the number of affected rows in a message box ??
here is my code for updating the table ...
For Each row As DataGridViewRow In DataGridView1.Rows
req = row.Cells(Column1.Name).Value
If row.Cells("Column1").Value = True Then
[Code].....
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Aug 4, 2011
in my tableadapter query i have a count function "COUNT(PRIMVENDOR)" to give me the number of rows in each group by:
SELECT VENALPHA, PRIMVENDOR, [GROUP], COUNT(PRIMVENDOR) AS GrpCount
FROM ViewCurrentMasterFile
WHERE (PRIMVENDOR = @VenNum)
[Code].....
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Aug 17, 2009
I'm having trouble adding child elements to the below
<securities>
<security id="040104JC6">
[code]....
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Sep 28, 2011
I'm using LINQ to compare two DataSets with each other to create new rows and update existing. I've noticed that the complete comparison lasts ~1,5 hours and only one of the two cores is busy(Task-Manager is 50-52% CPU Usage). I assume that it could increase performance significantly.
how and what should I parallelize?
These are the original queries(reduced to the essentials):
'check for new data
Dim srcUnique = From row In src.Email_Total
Select Ticket_ID = row.ticket_id, Interaction = row.interaction, ModifiedAt = row.modified_time
[Code].....
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Jun 17, 2011
C# or VB.NET is fine. I'd like to count number of people for each country from the following tables with LINQ to SQL I have two tables, one is Countries and other is People. It's one to many relatoionship from Countries to People. ountries table column:CountryId,CountryName People:PeopleId,FullName,CountryId (a primary key from Country table and allowed null) I want to count how many people each country has and get something like the following result that shows only the country that has people. Because there are some countries that have no people in the People table.
[Code]...
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Jan 25, 2012
What I have right now is this:
Dim users = From users In tempTable _
Distinct Select users.Item("s_userid")
Dim usersCount As Integer = users.Count
But I pretty sure I shouldn't have to do that. I should be able to get the count in/from that first linq query.
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Dec 5, 2011
I have this linq to entity
From r In ReceiptRepository.Fetch
Where
r.RECEIPTDATE >= ReportStartDate And
[Code]....
This is working fine, except the count property, it is just giving the number of group count. I don't know how to find out each Tender Count
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Jan 15, 2009
I have to perform the following SQL query: select answer_nbr, count(distinct user_nbr)
from tpoll_answer where poll_nbr = 16 group by answer_nbr The LINQ to SQL query
[Code]...
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Mar 31, 2012
Dim mydata = (From c In dc.Table Select New With {c.ID}).Count
any faster than this:
Dim mydata = (From c In dc.Table Select c).Count
[code].....
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Aug 2, 2011
I write the code below. I want to make short using linq count.
Dim query0 = From obj In dtAginglist _
Where (obj.Field(Of String)("CurrentStatus") = "Open" Or obj.Field(Of String)("CurrentStatus") = "Acknowledge") _
[Code]....
I try to use code below but it dosen't work with if source is datatable.
Dim orderCounts = From c In customers New With { _
c.CustomerID, Key .OrderCount = c.Orders.Count() }
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Aug 31, 2011
I don't know if this is doable, maybe with Linq, but I have a List(Of MyType):
Public Class MyType
Property key As Char
Property description As String
End Class
And I want to create a Dictionary(Of Char, MyType) using the key field as the dictionary keys and the values in the List as the dictionary values, with something like:
New Dictionary(Of Char, MyType)(??)
Even if this is doable, internally it will loop through all the List items, I guess?
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Apr 2, 2010
I have a table with the below structure.
ID VALUE
1 3.2
2 NULL
4 NULL
5 NULL
7 NULL
10 1.8
11 NULL
12 3.2
15 4.7
17 NULL
22 NULL
24 NULL
25 NULL
27 NULL
28 7
I would like to get the max count of consecutive null values in the table.
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Mar 24, 2012
I have a Table:
[Code]...
I'm trying by LINQ-query (VB.NET) to return a count for distinct value of Objects, Stuffs and Colours for every Room:
[Code]...
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Aug 9, 2010
I am learning Linq, so bear with me. I have a class object that holds 4 other class objects with each holding a List(Of T) of the next. Think tiered classes. As these lists as built I need to search all the Group2 for all Group3 to see which Group3.units.count is the largest. "units" being a List(Of T). [code]
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Nov 9, 2011
I'm very new to linq and I'm trying to come up with a linq query against a dataset that will return a max count value based on grouping records.[code]...
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Dec 8, 2010
I'd take both C# and VB.NET suggestion.I'm using LINQ to query data. I'm trying to query the parent and count the child tags.Here's my Tags table column:
TagId (int primary)
TagName
ParentId (int Allow NULL referred to TagId column)
Here's some sample data:
[Code]...
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Apr 17, 2012
I have a the following Class structure. Company > List(of Departments) > List(of Employees) I want to Query a Company to find out if it has a department of the following name and a Employee in that department with the following ID! How could I query this. The way I have the code it expect to return one department so I have it doing
[Code]...
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Mar 23, 2009
I have a requirement where I have to add items into a List(Of T) (let's call it Target) from an IEnumerable(Of T) (let's call it Source) using Target.AddRange() in VB.NET.
Target.AddRange(Source.TakeWhie(Function(X, Index) ?))
The ? part is a tricky condition that is something like: As long as the as yet unenumerated count is not equal to what is needed to fill the list to the minimum required then randomly decide if the current item should be taken, otherwise take the item.Somethig like...
Source.Count() - Index = _minimum_required - _curr_count_of_items_taken _
OrElse GetRandomNumberBetween1And100() <= _probability_this_item_is_taken
' _minimum_required and _probability_this_item_is_taken are constants
The confounding part is that _curr_count_of_items_taken needs to be incremented each time the TakeWhile statement is satisfied. How would I go about doing that? I'm also open to a solution that uses any other LINQ methods (Aggregate, Where, etc.) instead of TakeWhile.If all else fails then I will go back to using a good old for-loop =)
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Oct 30, 2009
I am thinking of dialling the number and if it rang then it is existing but I am not sure how to implement such. I am on Vista and it looks like all comm ports are not available or that I don't know how to enable them. Upon googling I have found samples of TAPI but I am unable to make them work, the following code is supposed to call a phone no. but I am getting the exception "Value does not fall within the expected range." on the 2nd line and I am clueless as to how to fix it
[code]...
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Feb 28, 2012
I have the following SQL query to return all Customers who have no OrderLines with no Parts assigned - i.e. I only want the customers within which every order line of every order has no parts assigned - (in the actual problem I am dealing with a different domain but have translated to customers/orders to illustrate the problem)
SELECT c.Customer_PK
FROM Customers c
INNER JOIN Orders o[code].....
This works but generates less than optimal SQL - it is doing a subquery for Count on each row of the customers query rather than using Group By and Having. I tried making the LINQ Group By syntax work but it kept putting the filter as a WHERE not a HAVING clause.Edit in response to Answers below: I am accepting JamieSee's answer as it addresses the stated problem, even though it does not produce the GROUP BY HAVING query I originally had.I am a VB developer so I have had a crack translating your code to VB, this is the closest I got to but it does not quite produce the desired output:
Dim qry = From c In context.Customers
Group Join o In context.Orders On c.Customer_PK Equals o.Customer_FK
Into joinedOrders = Group[cod].....
The problem I had is that I have to push "jl" into the Group By "Key" so I can reference it from the Where clause, otherwise the compiler cannot see that variable or any of the other variables appearing before the Group By clause.With the filter as specified I get all customers where at least one order has lines with no parts rather than only customers with no parts in any order.
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