.net - Create New Distinct List(of T) From Existing List(of T) Using LINQ?
Jun 1, 2011
How can I get a new distinct list from an existing list using LINQ? This is what I have so far and it is not distinct but does give me a new list.
Dim tmpQryColumn = (From a In _allAudits
Select New CheckBoxListItem
With {.Id = a.AuditColumn, .Name = a.AuditColumn}
).Distinct()
_columnList = New List(Of CheckBoxListItem)(tmpQryColumn)
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?
I figure I should use 'Aggregate' but apparently I am getting it wrong First I get a list of my Entity objects Dim employers As List(Of myEntity) = (New XXXX()).getZZZ(userName, userType) Then I figured this would be a way to put all the names in a string Dim names as String = employers.Aggregate(Function(current, [next]) current.Name & " " & [next].Name)
I have two generic lists, named ListA and ListB. Both ListA and ListB could potentially have duplicate items. What I would like to do is use LINQ to grab the items in ListB that are not in ListA, but I'm unsure how to do so.
I'm basically brand new to LINQ. I've seen some examples that allow me to strong type objects using LINQ but I don't really understand them because they're in C#, which I guess lets you do different things with LINQ(I think?). [Code] I just want to get a list of all the products from the XML doc and put them into a Generics list.
II am trying to create a toggle button that switches a list to a range and then back to a list if needed. I am able to get it to do both but when I add an item to the list, convert to a range and then convert back to a list it leaves off the last items I entered.I tried to work in a code to select all cells but I must not be putting it in the right place.This is what I have so far:
I load a list from a database like the example below. The class has more properties that the database table holds so when I load the list from the DB, there are Null values for certain properties of each item in the list. When I try List = List.Distinct.ToList, it never works (when null values are present).
I want to display distinct items from a column in a checked list box then make a selection or selections and perform commands based on info from a second column in that database the database is a small Access 2010 database in the application directory right now I added the data source and items dont display even though I selected that source in the checked list box properties
Dataset = MyDataSet1 CheckedListBox = MyListBox1
I tried it with a combo box and it shows items but includes duplicates, did I setup the datasource wrong?
I need to get a list of distinct names inside the data table and the sum of values for each one. I know some basic stuff about linq, but i don't know how to put the distinct and the sums together.
i am trying to create a list of list in that i would like to work on multiple accounts at the same time. lets say i have 5 accounts. every account has a seperate name. each account has a few fields. so i though of having a list of bookkeeping (with 5 accounts) and a list of accounts (with expense, income, tax, status, etc as fields). [code] and if the idea of using list of list works how do i loop through both lists.
I would like to create list of child objects from list of parent object. Like If i have list of bookingroom which has one member room then i would like to create list of room from it.
eg. code:
Dim BookingRoomList As List(Of BookingRoom) = New List(Of BookingRoom) Dim RoomList As List(Of Room) = New List(Of Room) BookingRoomList = BookingRooms.FillGrid()
[Code]....
Is there any short cut method instead of iterating over for earch?
This is probably a really basic question - but I have a list of items (custom objects) being passed from one winform (.net 3.5) to another. I want to create a local list to store changes that only get persisted if the user clicks save. Currently if the user clicks cancel - the changes are still applied in the first form because I assume the objects are reference type.I have the save working as it calls a service layer to do the save and then refreshes the other form - but not the cancel.
I am able to only add controls that are of type TextBox. My question to you is, can I create a List to hold more than one control type or do I have to create a list for each control type?
I am trying to use linq to query a List(of T) object, but when i type in my linq statement it comes back with the following error: Error57Expression of type 'System.Collections.Generic.List(Of BreakoutData)' is not queryable. Make sure you are not missing an assembly reference and/or namespace import for the LINQ provider.D:\Code\OLGA35\BreakoutByBusinessUnit.aspx17025D:\Code\OLGA35\
I have looked at my web.config and I have the imports:
I am trying to use linq to query a List(of T) object, but when i type in my linq statement it comes back with the following error:
Error57Expression of type 'System.Collections.Generic.List(Of BreakoutData)' is not queryable. Make sure you are not missing an assembly reference and/or namespace import for the LINQ provider.D:\Code\OLGA35\BreakoutByBusinessUnit.aspx17025D:\Code\OLGA35\
I'm using a program see here: Visual Basic Regular Expression Question. I enter letters and the program returns all possible combinations from list. I want change this line of code...
Dim result = fruits.Where(Function(fruit) Not fruit.Except(letters).Any())
If I have this list:
Dim fruit as List(Of string) from {"apple","orange","pear","banana"}
And I input "p a p l e r" then it would return "apple" and "pear", but if I enter "a p l e r" then it would return just "pear". The idea is to return all words, which can be made of entered letters without duplicating any single letter. How to optimize this Linq code?
Dim query = From o In myContainer.MyObjects Select o.MyStringProperty Distinct Dim myProperties As List(Of String) = query.ToList????? 'no way!!!' "query" type is IEnumerable(Of String)
I tried to use the query directly as a DataSource of a (infragistic) combobox, but it throws me NullReferenceException, so I decided to convert it to a listof strings, to be a more "classical" datasource.
Dim values As List(Of String) = query.AsQueryable().ToList() does not work either: Value of type 'System.Collections.Generic.List(Of System.Linq.IQueryable(Of String))' cannot be converted to 'System.Collections.Generic.List(Of String)'.