calc problem... :D

[DR00ME]

OK, lets say I got an Array which contains numbers from 0 to 255.....

 

like:

 

Dim MyArray(50) as byte

 

and it got values 4,4,4,7,6,3,230,100,2,1....n

 

now I want a code which calculate what number occur most... in this case it would be 4.

 

Or is there a function for this ?

[Nerseus]

I don't think there's anything built into .NET to do it, no. Do you have to use an Array? You can do some "nifty" stuff with a DataSet (it doesn't have to do database stuff) and its Compute and Select methods.

 

Writing code to do what you want is pretty trivial though, if you need it.

 

-nerseus

[Heiko]

There's no easy way to do that "in retrospective". You will have about 0.5*n^^2 operations if the array is of length (n). That sucks.

 

I recommend implementing an extra of object for this.

 

imports system.collections.specialized.
Class Counter

private mList as NameValueCollection
private mMax as integer = 0
private mMaxKey as string

public Sub Count (byVal Key as string)
  Dim curCount as integer
  if mList.contains(Key) then
     curCount = Convert.toInt32(mList(Key)) + 1
  else
     curCount = 1
  end if
  mList(Key) = CurCount

  if curCount > mMax then
     mMax = curCount
     mMaxKex = Key
 end if
end sub

Public Readonly Property MaxKey () as string
  Get
    return mMaxKey
  End Get
End Property

Public Readonly Property MaxCount () as integer
  Get
    return mMax
  End Get
End Property

 

Call the counter whenever a number is insertet to the array.

Edited February 20, 2004 by Heiko

[DR00ME]

Damn, love you guys lol :D I'm gonna try it!

 

Im also interested what nerseus got in his mind... I think he got a few tricks for dataSet... If you have energy to could you please show me a little example of it without using an array ? Never used dataSet I'm pretty new to vb.net anyway. I dont have to use an array neccessarily ....I might got one variable named x which is running some values between 0 and 255 so don't have to store 'em in an array.

 

P.S. There are over 70 000 numbers it is running between 0 and 255..... so basicly My array contains 70 000 numbers of type of byte and I have to find out which number occur most. But as I said earlier I do not have to store those 70 000 numbers in an array... just one variable going through those values.

 

P.S. nerseus what's the normal way to do it if I use an array ? and if I'm not using an array (dataSet?) ?

Edited February 20, 2004 by DR00ME

[DR00ME]

There's no easy way to do that "in retrospective". You will have about 0.5*n^^2 operations if the array is of length (n). That sucks.

 

I recommend implementing an extra of object for this.

 

imports system.collections.specialized.
Class Counter

private mList as NameValueCollection
private mMax as integer = 0
private mMaxKey as string

public Sub Count (byVal Key as string)
  Dim curCount as integer
  if mList.contains(Key) then
     curCount = Convert.toInt32(mList(Key)) + 1
  else
     curCount = 1
  end if
  mList(Key) = CurCount

  if curCount > mMax then
     mMax = curCount
     mMaxKex = Key
 end if
end sub

Public Readonly Property MaxKey () as string
  Get
    return mMaxKey
  End Get
End Property

Public Readonly Property MaxCount () as integer
  Get
    return mMax
  End Get
End Property

 

Call the counter whenever a number is insertet to the array.

 

"mList.contains(Key)"

 

I think there is no such a thing as .contains ?

it gives me error there.... did I miss something ?

 

also

 

curCount = Convert.toInt32(mList(Key)) + 1

 

why do you add 1 to the actual value ? or is the index added with 1 ? a bit confusing tough :D

Edited February 20, 2004 by DR00ME

[Heiko]

I wrote that down from memory. Sorry.

 

Try this.

 

Imports system.collections.specialized

Class Counter

Private mList As NameValueCollection
Private mMax As Integer = 0
Private mMaxKey As String

Public Sub Count (ByVal Key As String)

  Dim curCount As Integer

  Try
   ' Get the current number of elements for "key"
      curCount = Convert.ToInt32 (mList.Get(Key))
  Catch e as exception
    ' The Key was not in the list so far
     curCount = 0
   End try

   'Now add one, because we want to add this key 
   'another time

     curCount += 1

   'Check if this is a new maximum
  If curCount > mMax Then
     mMax = curCount
     mMaxKex = Key
 End If
End Sub

Public ReadOnly Property MaxKey () As String
  Get
    Return mMaxKey
  End Get
End Property

Public ReadOnly Property MaxCount () As Integer
  Get
    Return mMax
  End Get
End Property

End class

[Werdna]

There is a nicer solution

I don't know VB, but I'll write some pseude code that looks like VB

Dim Counts(256) as int
FOR (i=0; i<256; i++)
    Counts[i] = 0;

FOR (i=0; i<MyArray.Length; i++)
   Counts[MyArray[i]] = Counts[MyArray[i]] + 1

int maxIndex = 0;
int maxCount = Counts[0];

FOR (i=1; i<Counts.Lenght; i++)
{
  IF (Counts[i] > maxCount)
  {
       maxIndex = i;
       maxCount = Counts[i];
   }
}

 

basically Counts will hold number of times specific number will occur. Since your values are up to 256 it will hold 256 elements and we initialize it to 0

Then we loop thru your array and add 1 to each occurance of a number. Then we find maximum index in Counts.

So for input:

[4,4,4,7,6,3,230,100,2,1]

Counts array will look like:

[0, 1, 1, 1, 3, 0, 1, 1, ...]

 

I don't know if VB arrays are 0 index or 1 indexed, if it's one you'd need to adjust the code.

[DR00ME]

hmm I think the index of Counts goes out of range ? Edited February 20, 2004 by DR00ME

[DR00ME]

Finally got it working ....it got as many operations as the array lenght * lenght :( Edited February 20, 2004 by DR00ME