Calculate The Group By Count Of Keys In A Dictionary?
Nov 10, 2010
I have the following dictionary:
Dim idQueuedJobs As IDictionary(Of Int32, KeyValuePair(Of String, Int32)) = New Dictionary(Of Int32, KeyValuePair(Of String, Int32))
Why duplicate KeyValue pair? This is because the first Int32 is just a normal index, and the String followed by another Int32 contains systemnames and the priority of the qued job in idQueuedJobs
I want to calculate the total number of systemnames in idQueuedJobs, how can i obtain this count by using the groupby method?
Something like this maybe?
numberOfSystems As Int32 = idQueuedJobs.Values.GroupBy(...)
Dim Rooms As New Dictionary(Of Integer, Of Integer) Rooms(1) = 101, 102, 109, 110 Rooms(2) = 103, 104, 105 Rooms(3) = 106, 107
I want to know if i can obtain how many keys are in the dictionary For example, in this dictionary i have 3 keys, and if i use Rooms.Count it returns me 9 thats each pair of keys-values, but i want to obtain 3, each diferent value as key.
EDIT: Sintax error P.D: I cant use now because i have to use in a webservice filtered by IP, but VS2010 if i use count on the dictionary, tells me that will contain the number of the keys/value pairs.
I have this dictionary.. Dim Rooms As New Dictionary(Of Integer, Of Integer) Rooms(1) = 101, 102, 109, 110 Rooms(2) = 103, 104, 105 Rooms(3) = 106, 107
I want to know if I can obtain how many keys are in the dictionary. For example, in this dictionary i have 3 keys, and if I use Rooms.Count it returns me 9 that's each pair of keys-values, but I want to obtain 3, each different value as key. Syntax error. I cant use now because I have to use in a webservice filtered by IP, but VS2010 if I use count on the dictionary, tells me that will contain the number of the keys/value pairs.
I have a dictionary(of someType, someOtherType) (the types are immaterial). With a given value, I need to find all the keys that have that value in the dictionary. What I am currently doing is this:
Dim foundList as New List(of someType) For each key as someType in myDictionary.Keys If myDictionary(key) = givenValue Then
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Is there any reason to favor one of these approaches over the other when inserting into a generic dictionary with the possibility of a key conflict? I'm building an in-memory version of a static collection so in the case of a conflict it doesn't matter whether the old or new value is used.
If Not mySettings.ContainsKey(key) Then mySettings.Add(key, Value) End If
I have a VB.NET project where I am able to iterate through the keys and values collections of a dictionary object using an index:
MyDictionary.Keys(idx) MyDictionary.Values(idx)
When this code is taken from the test project and placed into the real project I get the following error:
'System.Collections.Generic.Dictionary(Of Double, String).KeyCollection' cannot be indexed because it has no default property.[code]...
In the line in sub search that says "dtf.Keys(idx) = 0" place your cursor after the right parenthesis and backspace you should get a tooltip that says, "<Extension> ElementAtOrDefault(index as Integer) as Double - index: the zero based element of the index to retrieve.
I have a generic dictonary which is templated in the following manner:
[code...]
If I wanted to omit certain list items against arbitrary keys (that is the items that are in the list contained within the value part of each of the key value pairs making up the dictionary) given some arbitrary condition (lets say omitting list items where a list item contained the string "abc")
I would expect to able to create/project into a new dictionary which would contain entries which contained lists WITHOUT those items whose name contained "abc"
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Private Sub cboAType_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboAType.SelectedIndexChanged ListView1.Items.Clear() If Not cboAType.Text = "-" Then
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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].....
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Me.Text = e.keycode
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Function GetWeldAuditInfo(ByVal ResourceId As String, ByVal VendorId
countDictionary As Dictionary(of Category, Dictionary(of Date, Integer))
The Class has a Enumeration Property. For the purposes of demonstration, I'll call it MasterCategory.I have been trying to get out an object that looks like the following:
groupedCountDictionary As Dictionary(of MasterCategory, Dictionary(of Date, Integer)
Which results in a IEnumerable (Of Dictionary(of Date, Integer)) for each MasterCategory value.However, I need that IEnumerable of Dictionary flattened to one dictionary with all the integers summed (total counts) for each date. I then tried to use various selects and group bys (from numerous stackoverflow posts) to "flatten" it, but my efforts have fallen short.
Current Code
[Category Class] - MasterCategory As Enum - Name As String etc
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