How can this code be accomplished using ToDictionary() instead of a For Each
Dim stringDict As Dictionary(Of String, String) = new Dictionary(Of Integer, String)
Dim stringList As List(Of String) = {"alpha", "beta", "gamma", "delta"}
For Each stringItem As String In stringList
stringDict.Add($"Entry{stringDict.Count+1}",stringItem)
Next
This is what I am trying to do:
Dim stringDict As Dictionary(Of String, String) = stringList.ToDictionary(Function(a) $"Entry{?}", Function(b) b)
I was hoping there might be a variable with the current row or index, or an incrementor
You can use the overload of Select that gives you the index:
Dim stringDict As Dictionary(Of String, String) = stringList.
Select(Function(s, index) (Key:=$"Entry{index + 1}", Value:=s)).
ToDictionary(Function(kv) kv.Key, Function(kv) kv.Value)
However, i find your loop more readable. You should also set Option Strict to On, following should give you a compiler error:
Dim stringDict As Dictionary(Of String, String) = new Dictionary(Of Integer, String)
You can use Enumerable.Range (documentation) to create a range of numbers from 1 to the Count of your List and then Enumerable.ToDictionary (documentation) to convert that range to a Dictionary.
Example:
Dim stringList As New List(Of String) From {"alpha", "beta", "gamma", "delta"}
Dim stringDict = Enumerable.Range(1, stringList.Count).ToDictionary(Function(i) $"Entry{i}", Function(i) stringList.Item(i - 1))
Fiddle: https://dotnetfiddle.net/4xHp9g
Related
I have 2 string, both split by (" ") and both around 40 different sub strings, first one called dick is the would-be keys, and the other one called dicv is the would-be values, how can I fill a dictionary with those?
I tried this:
Dim dicty As New Dictionary(Of String, String)
For Each kvp As KeyValuePair(Of String, String) In dicty
dick = kvp.Key
dicv = kvp.Value
Next
dick is the string with keys and dicv the one with values.
But I receive error "string cannot be converted to string()" when assigning dick and dicv as kvp.key and kvp.value.
Thank you very much.
I am guessing from the error that dick and dicv are declared as arrays. The following is how you assign values to arrays. ArrayVariable(index) = value
Private Sub ConvertDictionaryToArrays()
Dim dicty As New Dictionary(Of String, String)
Dim dick(dicty.Count - 1) As String
Dim dicv(dicty.Count - 1) As String
Dim index As Integer = 0
For Each kvp As KeyValuePair(Of String, String) In dicty
dick(index) = kvp.Key
dicv(index) = kvp.Value
index += 1
Next
End Sub
Private Sub FillDictionary()
Dim dicty As New Dictionary(Of String, String)
Dim dick(39) As String 'Guess that you have both of these arrays
Dim dicv(39) As String
For i As Integer = 0 To dick.Length - 1
dicty.Add(dick(i), dicv(i))
Next i
End Sub
I have an array "string()" with 3 element (2,5,6)
How do I convert all of element from string to int?
I tried CInt and Array.ConvertAll but they didn't work.
Please show me the way to do that. Thank you.
You have not said what type of problem you are having using Array.ConvertAll or shown your implementation of it, but this works for me.
Module Module1
Sub Main()
Dim mystringArray As String() = New String() {"2", "5", "6"}
Dim myintArray As Integer()
myintArray = Array.ConvertAll(mystringArray, New Converter(Of String, Integer)(AddressOf StringToInteger))
End Sub
Function StringToInteger(st As String) As Integer
Return CInt(st)
End Function
End Module
You can use the List(Of T).ConvertAll
Dim stringList = {'2','5','6'}.ToList
Dim intList = stringList.ConvertAll(Function(str) Int32.Parse(str))
Dim stringList() As String = {"2", "5", "6"}' string array
Dim intList() As Integer = {0, 0, 0, 0, 0}'integer array initialized with 0
For i As Integer = 0 To stringList.Length - 1
intList(i) = CInt(stringList(i))
Next
'Display the list
For i = 0 To intList.Length - 1
MsgBox(intList(i))
Next
This works like a charm:
Dim strArr As New List(Of String)(New String() {"2", "5", "6"})
Dim intList As List(Of Integer) = strArr.ConvertAll(New Converter(Of String, Integer)(AddressOf Integer.Parse))
No need to define a custom parser. Have look at its documentation as well:
My VB is rusty but I would do something like this:
intList = (From s in stringList Select CInt(s)).ToArray()
Just use a lambda,
Dim intList As IList(Of Integer)
Dim list1 = "1,2,3".Split(",")
intList = list1.ConvertAll(Function(s) Integer.Parse(s))
or
Dim intList As IList(Of Integer)
Dim list1 = "1,2,3".Split(",")
intList = list1.ConvertAll(AddressOf Integer.Parse)
Hopefully a simple question to most programmers with some experience.
What is the datatype that lets me do this?
Dim lstOfStrings as *IDK*
Dim String0 As String = "some value"
Dim String1 As String = "some value"
Dim String2 As String = "some value"
Dim String3 As String = "some value"
Dim String4 As String = "some value"
Dim String5 As String = "some value"
lstOfStrings.add(String0, String1, String2, String3)
I would access these like this
Dim s1 = lstOfStrings(0)
Dim s2 = lstOfStrings(1)
Dim s3 = lstOfStrings(2)
Dim s4 = lstOfStrings(3)
if I use List(of String)
I am only able to .add one thing to the list (at a time), and in my function I want to be able to store several values(at a time).
Solution:
Private Function Foo() As List(Of String)
Dim temp1 As String
Dim temp2 As String
Dim temp3 As String
Dim temp4 As String
Dim temp5 As String
Dim temp6 As String
Dim inputs() As String = {temp1, temp2, temp3, temp4, temp5, temp6}
Dim lstWriteBits As List(Of String) = New List(Of String)(inputs)
Return lstWriteBits
End Function
List(Of String) will handle that, mostly - though you need to either use AddRange to add a collection of items, or Add to add one at a time:
lstOfString.Add(String1)
lstOfString.Add(String2)
lstOfString.Add(String3)
lstOfString.Add(String4)
If you're adding known values, as you show, a good option is to use something like:
Dim inputs() As String = { "some value", _
"some value2", _
"some value3", _
"some value4" }
Dim lstOfString as List(Of String) = new List(Of String)(inputs)
' ...
Dim s3 = lstOfStrings(3)
This will still allow you to add items later as desired, but also get your initial values in quickly.
Edit:
In your code, you need to fix the declaration. Change:
Dim lstWriteBits() As List(Of String)
To:
Dim lstWriteBits As List(Of String)
Currently, you're declaring an Array of List(Of String) objects.
You can do something like this,
Dim lstOfStrings As New List(Of String) From {"Value1", "Value2", "Value3"}
Collection Initializers
Neither collection will let you add items that way.
You can make an extension to make for examle List(Of String) have an Add method that can do that:
Imports System.Runtime.CompilerServices
Module StringExtensions
<Extension()>
Public Sub Add(ByVal list As List(Of String), ParamArray values As String())
For Each s As String In values
list.Add(s)
Next
End Sub
End Module
Now you can add multiple value in one call:
Dim lstOfStrings as New List(Of String)
lstOfStrings.Add(String1, String2, String3, String4)
look to the List AddRange method here
Sometimes I don't want to add items to a list when I instantiate it.
Instantiate a blank list
Dim blankList As List(Of String) = New List(Of String)
Add to the list
blankList.Add("Dis be part of me list") 'blankList is no longer blank, but you get the drift
Loop through the list
For Each item in blankList
' write code here, for example:
Console.WriteLine(item)
Next
You can use IList(Of String) in the function :
Private Function getWriteBits() As IList(Of String)
Dim temp1 As String
Dim temp2 As Boolean
Dim temp3 As Boolean
'Pallet Destination Unique
Dim temp4 As Boolean
Dim temp5 As Boolean
Dim temp6 As Boolean
Dim lstWriteBits As Ilist = {temp1, temp2, temp3, temp4, temp5, temp6}
Return lstWriteBits
End Function
use
list1.AddRange(list2) to add lists
Hope it helps.
For those who are stuck maintaining old .net, here is one that works in .net framework 2.x:
Dim lstOfStrings As New List(of String)( new String(){"v1","v2","v3"} )
I declare my 2D lists:
Dim _invoiceitems As New List(Of List(Of String))
Dim _dbitems As New List(Of List(Of String))
Each List is filled like this:
Example Code To fill:
_invoiceitems.Add(New List(Of String))
_invoiceitems(0).Add("Code #")
_invoiceitems(0).Add("Quantity")
Well, now i need a third list called (_changesitems) Note that this result with the differences:
be the result of subtraction of quantities if this is found (dbitems - invoiceitems).
How i can get this result?
The following code will generate the results you are looking for:
Private Function getChangesItems(ByVal invoiceItems As Dictionary(Of String, Integer), ByVal dbItems As Dictionary(Of String, Integer)) As Dictionary(Of String, Integer)
Dim changesItems As Dictionary(Of String, Integer) = New Dictionary(Of String, Integer)()
Dim allCodes As List(Of String) = New List(Of String)()
allCodes.AddRange(invoiceItems.Keys)
allCodes.AddRange(dbItems.Keys)
For Each code As String In allCodes
If Not changesItems.ContainsKey(code) Then
Dim dbQuantity As Integer = 0
Dim invoiceQuantity As Integer = 0
If dbItems.ContainsKey(code) Then
dbQuantity = dbItems(code)
End If
If invoiceItems.ContainsKey(code) Then
invoiceQuantity = invoiceItems(code)
End If
Dim changeQuantity As Integer = dbQuantity - invoiceQuantity
If changeQuantity <> 0 Then
changesItems.Add(code, changeQuantity)
End If
End If
Next
Return changesItems
End Function
I used dictionaries instead of lists as was recommended by others. As long as your data only contains a code and a value, the dictionary is a better fit. If you have more columns, I would suggest creating a class that contains properties for each column and then make a list of that class type, rather than a simple 2D list of strings. Doing so would be more type-safe and easier to read.
I know I can do this with a for loop cause that's how i'm doing it now. I was hoping for a more efficient way to accomplish the task.
I have a dictionary(Of Integer, Boolean)
or Of String, Boolean.
i want to get a list(of integer) or Of String from the dictionary where all the values are true(or false depending on what i need at the time)
and to generalize it or "black box" it, it could be any dictionary(of whatever, whatever)
and return a list(of whatever) where the value = whatever i'm looking for at the time.
string, string where value = "Closed"
in short: i want all list of all the keys who's value = some criteria
my current code:
Public Function FindInDict(Of tx, ty)(thedict As Dictionary(Of tx, ty), criteria As ty) As List(Of tx)
Dim tmpList As New List(Of tx)
For xloop As Integer = 0 To thedict.Count - 1
If CType(thedict(thedict.Keys(xloop)), ty).Equals(criteria) Then
tmpList.Add(thedict.Keys(xloop))
End If
Next
Return tmpList
End Function
You can do this easily with Linq:
Public Function FindInDict(Of tx, ty)(thedict As Dictionary(Of tx, ty), criteria As ty) As List(Of tx)
Return (From kvp In thedict
Where kvp.Value.Equals(criteria)
Select kvp.key).ToList()
End Function
Use LINQ, like so:
Dim tStorage As Dictionary(Of String, String) = New Dictionary(Of String, String)
Dim tKeys As List(Of String) = New List(Of String)
Dim tCriteria As List(Of String) = New List(Of String)
tStorage.Add("One", "Uno")
tStorage.Add("Two", "Dos")
tStorage.Add("Three", "Tres")
tStorage.Add("Four", "Quatro")
tCriteria.Add("Dos")
tCriteria.Add("Quatro")
tKeys = (From k In tStorage.Keys Where tCriteria.Contains(tStorage(k)) Select k).ToList
For Each tKey As String In tKeys
Console.WriteLine(tKey)
Next
Console.ReadKey()