How to extract and plot only minimal and maximal peaks of an array , -graph analysis- With Matlab or excel

Question

I\'m doing video analysis.
The end result array I get is something like:

signal =

    Columns 1 through 7

       73960       73960       73960       73         


        

Answer 1

This VBA

• Reads the data from column A and B into a variant arrays
• Find the local minima and maxima and extracts that to second array
• Creates a brand new chart of the minima/maximia (see image)

     Sub NewGraph()
    Dim X
    Dim Y
    Dim lngRow As Long
    Dim lngCnt As Long
    Dim Chr As ChartObject

    X = Range([a1], Cells(Rows.Count, "b").End(xlUp))
    Y = Application.Transpose(X)

    For lngRow = 2 To UBound(X, 1) - 1
        If X(lngRow, 2) > X(lngRow - 1, 2) Then
            If X(lngRow, 2) > X(lngRow + 1, 2) Then
                lngCnt = lngCnt + 1
                Y(1, lngCnt) = X(lngRow, 1)
                Y(2, lngCnt) = X(lngRow, 2)
            End If
        Else
            If X(lngRow, 2) < X(lngRow + 1, 2) Then
                lngCnt = lngCnt + 1
                Y(1, lngCnt) = X(lngRow, 1)
                Y(2, lngCnt) = X(lngRow, 2)
            End If
        End If
    Next lngRow

    ReDim Preserve Y(1 To 2, 1 To lngCnt)

    Set Chr = ActiveSheet.ChartObjects.Add(250, 175, 275, 200)
    With Chr.Chart

        With .SeriesCollection.NewSeries
            .XValues = Application.Index(Application.Transpose(Y), 0, 1)
            .Values = Application.Index(Application.Transpose(Y), 0, 2)
        End With
        .ChartType = xlXYScatter
    End With

End Sub