How to count string occurences in a list(Of String)

Question

I am looking to dynamically count from a list, how many times items have occured. I can do it below if I specify the value I am looking for, but what I am really looking to do is to iterate through my list, count occurences, and total them out. My current code is below:

Dim itemlist As New List(Of String)
itemlist.add("VALUE1")
itemlist.add("VALUE2")
itemlist.add("VALUE3")


    Dim count As Integer = 0

    For Each value In itemlist

        If value.Equals("VALUE1") Then count += 1

    Next

 Msgbox(count.tostring)

So my point would be instead of searching for the value, let the app total them up and display the counted occurences it to the user, similar to a "COUNTIF" in excel. I cant find much on this without using LINQ, Thanks

So you don't want to use LINQ or a for loop. What are you looking for? Could you provide a sample output? — deepee1
– deepee1, Commented Feb 20, 2013 at 18:56
I could use linq, I just figured there would be a simple way using lists to count duplicates. For example, if my list contained "RED", "RED", "RED", "GREEN", It would output RED - 3, GREEN - 1 — Jason Bayldon
– Jason Bayldon, Commented Feb 20, 2013 at 19:12

Meta-Knight · Accepted Answer · 2013-02-20 19:31:56Z

8

You can do this very easily with LINQ:

Msgbox(itemlist.Where(Function(value) value = "VALUE1").Count)

To count duplicates, once again it's easy with LINQ:

Dim itemlist As New List(Of String)
itemlist.Add("RED")
itemlist.Add("RED")
itemlist.Add("RED")
itemlist.Add("GREEN")

dim groups = itemList.GroupBy(Function(value) value)

For Each grp In groups
    Console.WriteLine(grp(0) & " - " & grp.Count )
Next

Output:

RED - 3
GREEN - 1

edited Feb 20, 2013 at 19:31

answered Feb 20, 2013 at 19:18

Meta-Knight

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1 Comment

Jason Bayldon Over a year ago

Thanks. I intend however to populate based on whats occuring in the list. For example, Lets say my list generates "RED", "RED", "RED", "BLUE". I want to display the occurence value as "RED" - 3, "BLUE" - 1. But what if "GREEN" shows up in the list? I would like to just populate each uniquely and then count the duplicates instead of searching for a set value

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