Peak over treshold method - VBA - Excel - vba

Question

I really hope you can help me with the following question.
I have a dataset and I need to filter for some values. This is a dataset for wave analysis, and I need to filter out for the higstest values. The so called peak over treshold method. I want to filter out the storms in de wave dataset.
I can do this with the following: A storm is defined when the waveheight is above a certain value, for example 2.5 meters. The waveheight is measured every 3 hours.
So in the dataset I can do an If(B3>$A$1; B3;0). A1 = 2,5 m. Now I have filtered for waveheights. So now I can see in my dataset rows straight after each other with values higher than 2,5 meters, because a storm last serveral hours. See picture 1 as example:
[Picture 1][1]
So if a certain value is above X, then return that value, otherwise return zero. Now comes the hard part:
Now I need the highest value of that strip for values above 2,5 meters. As this is a big(!) dataset, I have a lot of datapoints. So I have several 'storms', which don't always last as long. So the values that are higher than 2,5 meters aren't always 3 rows, sometimes more. See picture 2picture 2
I need to compute the highst value in Column i, for each storm. Because each storm doens't last as long, I probally need to write code in VBA. Could anybody help me with this? I've been stuck for 6 days, but my VBA code doens't work and I do not have much experience with VBA. If anybody could help me that would be very much appreciated!
Kind regards,
Jeroen
EDIT as a reply on -Excel Developers-
I think I'm almost there, thank u very much for replying!! I am probably misreading the code, but a I have still a slight difficulty in computing the highstest value for each storm I think it should look something like this, as seen in picture 3.Picture 3
The highest value of each storm should be printed in the next column, as seen in picture 3. It probably says it all in the code, but I am misreading it.
Thank u very much for you answer! I really hope you can help me with the last part :-)
Kind regards,
Jeroen

Answer 1

You will have to iterate over all the values in column i. For every storm, find the highest value. A storm starts when a 0 is followed by a positive value, and ends when a positive value is followed by a 0. So something like this:
Sub FindHighestValue()
Dim vData As Variant
Dim Storms As Collection
Dim ndx As Long
Dim ndxStorm As Long
Dim MaxValue As Double
Dim Previous As Double
Dim InStorm As Boolean
vData = Sheet1.Range("I8:I21").Value 'Change this to whatever range your wave heights are in
Set Storms = New Collection
Previous = 0
InStorm = False
For ndx = LBound(vData, 1) To UBound(vData, 1)
If vData(ndx, 1) > 0 And Previous = 0 Then
'A storm has started
MaxValue = vData(ndx, 1)
InStorm = True
End If
If InStorm And vData(ndx, 1) > MaxValue Then
MaxValue = vData(ndx, 1)
End If
If (vData(ndx, 1) = 0 And Previous > 0) Or (ndx = UBound(vData, 1)) Then
'A storm has ended
InStorm = False
Storms.Add MaxValue
End If
Previous = vData(ndx, 1)
Next
If Storms.Count > 0 Then
For ndx = 1 To Storms.Count
Debug.Print ndx & ": " & Storms(ndx)
Next
End If
End Sub