Finding the biggest and smallest values with most counts in histogram - vb.net

Question

I built a program to create a text based histogram from an image.
Now I need to pick up the data from the text file and find the biggest value with most counts and the smallest value with most counts.
This is an example from a generated text file:
0 1
1000 80
10004 2
10005 200
10006 2
1002 73
105 10
On the left, I have listed the pixel values and on the other side the counts.
So, here I get the value 10005 as the biggest with the highest count (200) and the value 1000 as the smallest with the highest count (80).
I know how to read the text file line by line, split the values and put them in an array.
The question is, how can I get what I want by the fastest way assuming that I'm working with large images generating long lists of values (hundreds) in the histogram text files?

Answer 1

The definition of minimum and maximum value is somewhat controversial here, but, following the description, the underlying logic could be that a minimun can be determined when a maximum has been found.
So, we could order the list (some hundreds lines of data is not really much) by descending (higher values first), evaluate a maximum value and, after that, determine the minimum:
Dim bitmapData = File.ReadAllLines("[Data File Path]").
Select(Function(bd) bd.Split(New String() {" "c}, StringSplitOptions.RemoveEmptyEntries).
Select(Function(n) Integer.Parse(n)).ToArray()).
OrderByDescending(Function(value) value(0)).ToList()
Dim max() As Integer = bitmapData(0)
Dim min() As Integer = {bitmapData(0)(0), 0}
For i As Integer = 1 To bitmapData.Count - 1
If bitmapData(i)(1) > max(1) Then
If bitmapData(i + 1)(0) < bitmapData(i)(0) Then
max = bitmapData(i)
End If
ElseIf bitmapData(i)(0) < max(0) Then
If bitmapData(i)(1) >= min(1) Then
min = bitmapData(i)
End If
End If
Next
Using your data sample and a comparison array of values, the results are:
Min ( 1030, 251) Min ( 1000, 80)
Max (10001, 260) Max (10005, 200)
--------------------------------------------
0 1 0 1
10001 260 1000 80
1000 80 10004 2
10004 2 10005 200
10005 200 10006 2
10006 2 1002 73
1002 73 105 10
105 10
50 250
51 220
1026 201
1030 251
1031 250
10009 252
10008 250
10007 251
Assuming that the data source is represented by two different arrays (named Pixels and Counts, here) which need to be synchronized (paired indexed values), you just need to substitute the BitmapData array with the Pixelsand Counts array:
Dim Pixels As Integer() = [Integer Source]
Dim Counts As Integer() = [Integer Source]
Dim max() As Integer = {Pixels(0), Counts(0)}
Dim min() As Integer = {Pixels(0), 0}
For i As Integer = 1 To Pixels.Count - 1
If Counts(i) > max(1) Then
If Pixels(i + 1) < Pixels(i) Then
max = {Pixels(i), Counts(i)}
End If
ElseIf Pixels(i) < max(0) Then
If Counts(i) >= min(1) Then
min = {Pixels(i), Counts(i)}
End If
End If
Next