Unique Items In A List
Nov 7, 2010
I am new to VB.NET 2008 and a few users on this forum have suggested using Generic Lists instead of the old VB6 model of Collections. I need to add to the list of several items to the list, but what is happening it it is changing the first item in the list when I add the second, so there are now of the same item in the list. How do I add unique items to the list? Also, in the collection world, I could define a index of an item by placing the index value into second item of the Add Function.
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Mar 8, 2012
How can I create a list (of my custom structure) to hold only unique items? This list should be created from another list.[code]...
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Jun 12, 2009
I am trying to grab all unique items from a DropDownList. Is there a simple way to do this?
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Oct 25, 2009
On the form load event i want to populate my ComboBox1 to display unique items directly from the DB. For that i have set the DataSource property of the ComboBox1 to the selected field. On the ComboBox1_SelectionChangeCommitted event i have set the filter for the DataSource which is working fine.
Now when i select an item from the ComboBox1 i get the filtered result in DataGridView but when i again drop down the combobox i see nothing other than the last selected item. Why is this happening? Is there a better way of populating ComboBox with the items directly from DB with default selected value as null?
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Nov 9, 2011
I have 2 List (of T) populated with the following
Dim curweekFolder As String
curweekFolder = String.Concat("c:", curweek_date.SelectedItem)
Dim preweekFolder As String
preweekFolder = String.Concat("c:", preweek_date.SelectedItem)
[code]....
I first wanted to identify which files matched in filename and list those in ListBox1, the following that was suggested on this forum worked very well (I added the minus last 19 characters as they would be different).
ListBox1.Items.AddRange(curlist.Where(Function(fi) prelist.Any(Function(fi2) fi.Name.Length - 19 = fi2.Name.Length - 19 AndAlso fi.LastWriteTime = fi2.LastWriteTime AndAlso fi.Length = fi2.Length)).ToArray)Now I need to populate ListBox2 with the files that do not match in each List (of T), again without looking at the last 19 characters. So for example if the first List (of T) had A.txt, B.txt and C.txt and the second List (of T) had A.txt and B.txt then ListBox1 would have A.txt and B.txt while ListBox2 would have C.txt.
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Dec 17, 2011
I'm trying to categorize articles by stored keywords. I have a list of keywords for a category, and I want an article to get assigned a category that has the most keyword count.
For Each keyword As String In category.Keywords
category.tempCount += Regex.Matches(article.Item("title").InnerXml, Regex.Escape(keyword)).Count
[code].....
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Jun 9, 2011
I'm having some problem here. I have a list of files to read and have to append them all to one unique file. the problem is that when i open the first file to read. I read the first line and discard it. when i read the second line, its empty ! but it is not in the original file. what im doing wrong ?
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Aug 12, 2011
this website seems great and this is my first post. Sorry if this has already been answered but I have been searching for a long time. I have a program with a list view in details mode. I have it load column settings (visibility, display index, width, etc.) when the form is opened and save them when closed. There are many columns...about ten so far...like folder, file, size, etc. Is there a way to access variable names from the values of other variables?
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Jul 3, 2011
I am having so trouble with the ToUpper() procedure with strings. I am using LINQ to find unique values in a list of objects. In that whole process I set the values to compare to all lowercase in order to get a proper list. My goal is to populate a dropdown list with the values. I'm attempting to set the first letter of of the string to uppercase and keep the rest lowercase however the toUpper() procedure is not working?
Private Function FixCase(ByVal strIn) As String
Dim strOutput As String
Dim intStringLength As Integer = strIn.Length - 1
strOutput = strIn.Substring(0, 1)
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Feb 24, 2009
I have a List (Of Type) which contains many instances of a class with three properties, IPAddress, AlertDate and AlertTime.There can be many duplicates of IPAddress in this list :-
[code]...
I need to be able to pull out just the latest (by date and time) entry in the list for each unique IPAddress. Is there any simple way of doing this?
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Apr 28, 2010
I want to combine multiple lists of items into a single list, retaining the overall order requirements. i.e.:
1: A C E
2: D E
3: B A D
result: B A C D E
above, starting with list 1, we have ACE, we then know that D must come before E, and from list 3, we know that B must come before A, and D must come after B and A.If there are conflicting orderings, the first ordering should be used. i.e.
1: A C E
2: B D E
3: F D B
result: A C F B D E 3 conflicts with 2 (B D vs D B), therefore requirements for 2 will be used.
If ordering requirements mean an item must come before or after another, it doesn't matter if it comes immediately before or after, or at the start or end of the list, as long as overall ordering is maintained.
This is being developed using VB.Net, so a LINQy solution (or any .Net solution) would be nice - otherwise pointers for an approach would be good.
Edit: Edited to make example 2 make sense (a last minute change had made it invalid)
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May 3, 2012
I have a stored procedure (I cannot edit) that I am calling via linq.
The stored procedure returns values (more complex but important data below):
Customer Stock Item Date Price Priority Qty
--------------------------------------------------------
CUST1 TAP 01-04-2012 £30 30 1 - 30
CUST1 TAP 05-04-2012 £33 30 1 - 30
CUST1 TAP 01-04-2012 £29 20 31 - 99
CUST1 TAP 01-04-2012 £28 10 1 - 30
I am trying to limit this list to rows which have unique Dates and unique quantities in LINQ. I want to remove items with the HIGHER priority leaving rows with unique dates and qty's.
I have tried several group by's using Max and order by's but have not been able to get a result.
Is there any way to do this via linq?
EDIT:
Managed to convert brad-rem's answer into VB.net.
Syntax below if anyone needs it:
returnlist = (From p In returnlist
Order By p.Qty Ascending, p.Priority
Group By AllGrp = p.Date, p.Qty Into g = Group
Select g.First).ToList
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Oct 1, 2009
I'm looping all the properties in an object via reflection:
For Each p As PropertyInfo In values.[GetType]().GetProperties()
If p.CanRead Then
'Do stuff
End If
Next
how to determine whether the property in question is a generic List(Of T)? If it is I need to loop the list itself.
I've experimented with GetType and TypeOf but have not managed to get anything working.
To clarify, I want to keep this generic. I do not want to specify the type of T, I need to loop the list items and call the ToString method on each item. T could be one of a number of different types (application specific reference types). Is it possible to do this without specifying types?
(VB.NET 2005 with .Net 2.0)
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Mar 16, 2011
This program is supposed to allow the user to check items in a checked list box. If the item is checked, it goes into the Completed List Box on the right. The program then adds the unchecked items to the Pending list box on the left. I keep getting placement values (e.g. O,1,2) instead of the strings (e.g. "Key Returned") in the list box results (see photo attached)
Public Class frmCheckOut
Dim i As Integer
Dim cleaning As String = "Cleaning Inspection"
Dim damage As String = "Damage Repaired"
[code].....
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May 16, 2011
Another program I am working on for fun, I am basically shuffling a list inside a listbox, what I want to do is delete the rest but not sure how to go through with that. At the moment I have this: [code] Just contains the code, declarations outside weren't included.So anyway, once clicked, it will call on the function to basically shuffle in a for loop, I was wondering if I should (or how should) create another function and call it in the click button or have just a loop in the click button so it deletes half the list. What I am doing is I have 20 list of items, I want the program to shuffle the items and then deleting the lower 10, meaning, if I had 10 items and wanted 5 top, I'd want: 0, 1, 2, 3, 4 and deleting 5, 6, 7, 8, 9.
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Feb 13, 2012
I am using VB .Net to access the eBay API and store all completed orders in a database. This database is then fed into a proprietary shipping system, which can not handle an order number larger than 20 characters. eBay returns an order number like so 230407279314-680141236013 which is too long. The order number is always 12 numbers a hyphen and 12 more numbers. What I need to do, is turn this (the result can be alpha numerical) into a shorter, unique order key to store in my database alongside the true orderId (so that this can be referenced by the shipping software instead of the actual order number). The reason for the 20 character limit is the barcode algorithm used. Is there any way to achieve this in VB .Net 2010? This number can be anything unique, so long as it does not exist already (even a good uniqueid function would work, but I would have to query the database to make sure it isn't taken)
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Jan 10, 2009
I'm using the datagridview. This is the sample data:
[Code]....
How do I parse through the grid to rename the duplicate values in a particular column (in this example it's the l_name field) into such a format?
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Jul 20, 2011
I am attempting to read the results from a SQL query into a List(Of) and I can see the List.count while adding items to the List increments, however in another part of my code when I am attempting to read the List the List.Count returns 0. My List is as follows:
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Apr 19, 2009
Let's say I have a menustrip, which has a category "Colors" for example, and in that category there is an option of 20 colors, but I want only 1 to be checked at any one time, now to do that with what I know, I'd have to check every other one of the check boxes and uncheck them in every single click event, is there no cleaner way to do this?
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Nov 27, 2009
I have an error panel that is subbed in to a page if an error goes wrong to gracefully handle and display errors.Currently, I am just appending the error messages to a string and pushing that to a label. If you have multiple errors, this gets messy.I'd like to push each error to a list item in a bulleted, unordered list.How can I dynamically generate, from a vb codebehind file, new list items inside of an undordered list element?
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Jan 25, 2011
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.
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May 5, 2010
i want to search item A (from a list of X items) in list B but i want to get the item not found example Search ITEM A in LIST B if not found then return a print....if found continue with ITEM B..and so on.
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May 23, 2012
That was probably bad title, but I'll illustrate what I'm trying to do. I have a method in a class that I need to call several times. The method returns a List(Of String). I'm just grabbing some information from a database.
VB.NET
Public Function GetTestList() As List(Of String)
Dim int As Integer = 0
[code]....
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Mar 21, 2011
How generate the unique no. 1,2,3 and so on .... on button click of each new user ..
the code mentioned below is a readwrite coding in vb.net ...
but the problem is it generate the same id for different users on button click event... but i want the no. of times button clicked the new ids will be generated
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim FILE_NAME As String = Server.MapPath("counts.vbi")
[Code].....
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May 30, 2011
I have a List(Of MyObj), and I want to iterate through that list and compare each element to all other elements in the same list, excluding (if possible) the same element. I have a solution that works, but it's slow and uses double For loops. It may possibly have also summoned Cthulhu from his sleep. This below is a sanitized version of what I have:
Dim MyList As New List(Of MyObj)({Obj1, Obj2, Obj3, Obj4, Obj5, Obj6})
If MyList.Count > 0 Then
For i = 0 To (MyList.Count - 1) Step 1
[code]....
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Mar 28, 2011
I am writing app in vb.net
I have two variables one with list of RoomRate and other with list of RoomTypes.
We have RoomRates and RoomTypes linked with RoomTypeInfo variable insite the RoomRate.
So how do i find the RoomTypes which donot have the RoomRates Defined.
My Sample Code:
class RoomType
property UIN as integer
property Title as string
end class
[Code]......
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Nov 15, 2011
I want to know how to test the 1st list box if it has items more than the other list box but by one item, here is what i have: If lstInvisibleTv. Items.Count > lstInvisiblePc.Items.Count Then it works good if the lstInvisibleTv list box is greater than the other list box by one but it also works if it is greater the other one by one or more which I do not want. I want it to work just by one.
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May 8, 2011
Unique constraint - these columns currently doesn't have unique values..?? I have created Unique Constraint with 3 columns. My code works perfectly but once - two users @ same time entered same data and somehow it saved in DB; after that incident. This UniqueConstraint gives me error - These columns currently doesn't have unique values. How can I check if user enters this kind of entry or how can I restrict the Entry?
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May 27, 2012
I have a program that will compare an array of grocery list items glist and an array of coupon item clist.When I compare the two and if there is a match somewhere in the array I want to have a picturebox visible.When there is no match, I want the picture box not to be visible. [code] The code seems to work great until I come to the else statement.When the code finds a match it displays the picture box and the msgbox without error, but as soon as the message box is cleared, even though i've input it as an ELSE statement, the picturebox goes false again.Does anyone have any idea of how I can "hold" the picturebox to stay visible while the match between the arrays exists?
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May 2, 2012
i am writing a program that reads a excel report from accounting software with our weeks orders on... so basically the program reads a list of around 100 items which all works fine.I also have a database that holds info on each item, when the excel sheet is parsed the software checks to see if any new items have been added to the list that are not on the softwares database. this is where i am having the issue.I have two lists: ItemsOrdered & ExistsingItems.
All the items ordered this week are in ItemsOrdered and all the items not in the items in the database are in the ExistsingItems list. using these two lists how can i find items that are in ItemsOrdered but not in ExistsingItems.
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