Get Distinct Values From List(Of T) Using Linq?

Mar 10, 2012

I have a List(Of Hardware) - the List is called HWModels

Class Hardware has the following Properties:

ModelName
Status
CPUStatus
MemoryStatus
DiskStatus

The List is populated by reading a CSV file, once it's populated, I want to return the distinct records based on the ModelName

I've attempted by doing it as follows:

(From a In HWModels Select a.ModelName).Distinct

But this isn't right because I end up with a list of only the ModelName's and nothing else.

How do I get the Distinct function to return all of the other class members within the list?

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I'm pretty new in Linq and the first problem I've is to select the Distinct values from a ObservableCollection( Of T)

I've tried with[code]...

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Jun 1, 2011

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Dim tmpQryColumn = (From a In _allAudits
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).Distinct()
_columnList = New List(Of CheckBoxListItem)(tmpQryColumn)

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Create New Distinct List(of T) From Existing List(of T) Using LINQ?

Mar 12, 2010

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}

[code]......

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Jul 2, 2011

Supposing the referenced List below contains 2 elements:
Dim Countries = From c In List _
Select New With { .Country = c.Country, .CountryID = c.CountryID }

The code above returns
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Oct 19, 2010

I have a datatable which has been dynamically generated from FoxPro tables using a UNION Select statement. e.g.SELECT * FROM x UNION SELECT * FROM y UNION SELECT * FROM Z ORDER By v_alue1This produces a datatable with about 100 rows, each containing many fields, one of which is c_olor. From this datatable, I would like to select the distinct colors and then output in a dropdown.I have a public class Color which just has one property which I can then use as the DataTextField and DataValueField for the dropdownlist

Public Class Color
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[code].....

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Dim query As IEnumerable(Of DataRow) =
(From row As DataRow In SourceTable.AsEnumerable() _
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[Code]....

I want another datatable with distinct row based on given columns from SourceTable.

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Nov 8, 2011

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[Code]...

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Oct 1, 2010

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Dim details = <Details>
<Vector size="5">
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<Item>Introduction</Item>
<Item>The Independence of Grammar</Item>

[Code]...

Is correct in that it returns the list of XElements I want (items 1 - 4, base 0), but I really just need a list of strings for the .Value of those XElements. Maybe I'm just dense here, but anything I've tried in the chapterTitles query isn't working (appending with .ToList.ToString, etc.). details.<Vector>.<Item>.Skip(1).Take(4).Value just returns the first XElement's value.

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Using LINQ To Find Unique Values In A List Of Objects?

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)

[code].....

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Firstname, Surname, City, Country as string variables.
Dim DataEnum As IEnumerable(Of frmTelephone.clsPerson) = alPerson.OfType(Of frmTelephone.clsPerson)()

[code].....

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Mar 18, 2010

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[Code]....

I would assume that this would create a new collection of anonymous types, that would be distinct. Instead it creates a collection the size of the "ThisParentCollection" with duplicate "MyAnonymousType" in it (duplicate id's).

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Oct 14, 2009

I have a very interesting LINQ question. I have a document, that I am trying to filter results on, but to filter, I am matching on a REGEX result from one element of the XML. I have the following, working LINQ to XML to get the individual data that I'm looking for.

[Code]...

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LINQ / Select Distinct From Dataset?

Aug 20, 2010

I have a single columned datatable inside a single tabled dataset.I just want to convert this dataset to distinct rows. Here is my code, it gives compile error '.' expected.

Dim query = _
From email In ds.Tables(0) _
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EDIT: I changed to (Of String) and it works... BUT NOW 'query' is an ienumerable collection of characters... not a datatable... so how do I convert back easily without manually doing a loop?

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Linq Join On Parameterized Distinct Key?

Sep 9, 2010

I'm trying to LINQ two tables based on a dynamic key. User can change key via a combo box. Key may be money, string, double, int, etc. Currently I'm getting the data just fine, but without filtering out the doubles. I can filter the double in VB, but it's slooooow. I'd like to do it in the LINQ query right out of the gate.

[Code]...

"Range variable name can be inferred only from a simple or qualified name with no arguments."

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Jun 9, 2011

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LinqMasterTable:
-------------------------------------------------------------
| AppleIndex | AppleCost | AppleColor | AppleDescription |
------------------------------------------------------------

[Code].....

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Jan 15, 2009

I have to perform the following SQL query: select answer_nbr, count(distinct user_nbr)
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[Code]...

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Jan 4, 2012

I've a collection with the data like this.[code]...

how can select the distinct data using linq?

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Sql Server - Linq - Limit List To 1 Row Per Unique Values Based On Value (minimum) Of Single Field

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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How To Group Distinct Columns In A Linq Query

Nov 4, 2010

The following data is created by joining two sql tables together:I would like to group together distinct rows of DateStamp/UserName/ StudentName/ InstructorName/TableName/PrimaryKey (I'll call this 'group records') and then group under these ColumnName/PreviousValue/NewValue (I'll call this 'subgroup records')The end result would be that I could iterate through the 'group records' - there would be 5. In each 'group record', I could then iterate through the 'subgroup records'. The 5 groups would contain 3, 2, 5, 2 and 1 subgroup records respectively.What would be the syntax to create a query to do this? Ideally this would be in a vb.net linq syntax.

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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 have the following table structure. I want to select distinct CustomerId and CustomerName, TotalCost.[code]

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Apr 2, 2010

I'm using LINQ to SQL to select some columns from one table. I want to get rid of the duplicate result also.

Dim customer = (From cus In db.Customers Select cus.CustomerId, cus.CustomerName).Distinct

Result:

1 David
2 James
1 David
3 Smith
2 James
5 Joe

Wanted result:

1 David
2 James
3 Smith
5 Joe

Can anyone show me how to get the wanted result?

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Select Distinct Rows From Datatable In Linq

Jul 14, 2010

I am trying to get distinct rows based on multiple columns (attribute1_name, attribute2_name) and get datarows from datatable using Linq-to-Dataset.[code]How to do thin Linq-to-dataset?

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Oct 24, 2011

I have a DataTable with about 64 columns, including "UserAnswer", "CorrectAnswer", and "QID_Lookup". I am building a LINQ that will select all the rows that have a correct answer (user answer matches correct answer), but I only want to select rows that have distinct "QID_Lookup".

[Code]...

The problem is that the result set includes duplicate QID_Lookup values. How can I include only distinct QID_Lookup values? keep in mind that there are 64 columns, so if I can avoid it, I wouldn't want to list each column individually for selection.

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C# - LINQ Select Distinct While Evaluating Multiple Rows

Jul 11, 2011

I have an EnumerableRowCollection that looks like the following:
VendorCode | GroupType | Variance
01165 G .16
01165 G .16
01165 CH .16
01165 CH .18
07754 G .25
07754 G .25
07754 G .39

Essentially, this is a massive list of vendor codes, their groups, and price variances. I need to compose a query that will create a distinct list vendor codes and group types. The catch, however, is that I need to evaluate all of the variances associated with that particular VendorCode/GroupType to see if they are all the same - it they are not, I need to return some way of signifying that the group has a "custom" variance, otherwise it needs to return the value (ie: if they are all .16, then return .16, if there are multiple values, return "custom")

The result would look like this, based off of the list I showed above.
VendorCode | GroupType | Variance
01165 G .16
01165 CH custom
07754 G custom

I have no trouble getting a distinct list of VendorCode/GroupType - this is what I have so far:
Dim distinctList = From q In query Select q.VendorCode, q.GroupType, (evaluated q.Variance here?) Distinct
(where "query" is an EnumerableRowCollection(Of (anonymous type)))
I'm at a loss, though, on how to evaluate the variance property to get the result that I need?

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Oct 19, 2010

My particular example is fairly complex but I think the concept would apply equally to something like a logging system so I'll use that instead for ease of explanation. It's a ficticious example, please don't harp on or agonise over what is achitectually, programatically or morally wrong with the example itself

[Code]...

I don't want to 'cheat' and resort to a long-winded way of doing it when performance isn't critical here and I'm moderately confident it can be done in a single LINQ statement.

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Aug 18, 2011

If I simply have this:>>

CODE:

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Oct 7, 2010

To revisit a previous question with a further stipulation..Anyone know how to do the following, IGNORING CASE?

[Code]...

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Apr 16, 2010

basically i'm trying to reproduce the following mssql query as LINQ

SELECT DISTINCT [TABLENAME], [COLUMNNAME] FROM [DATATABLE]

the closest i've got is

Dim query = (From row As DataRow In ds.Tables("DATATABLE").Rows _
Select row("COLUMNNAME") ,row("TABLENAME").Distinct

when i do the above i get the error

Range variable name can be inferred only from a simple or qualified name with no arguments.

i was sort of expecting it to return a collection that i could then iterate through and perform actions for each entry. maybe a datarow collection?

As a complete LINQ newb, i'm not sure what i'm missing.
i've tried variations on

Select new with { row("COLUMNNAME") ,row("TABLENAME")}

and get:

Anonymous type member name can be inferred only from a simple or qualified name with no arguments.

to get around this i've tried

Dim query = From r In ds.Tables("DATATABLE").AsEnumerable _
Select New String(1) {r("TABLENAME"), r("COLUMNNAME")} Distinct

however it doesn't seem to be doing the distinct thing properly.

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