Identifying The Highest Peak, And Return The Values That Is Low To The Right And Left Of Highest Peak, By Keeping The Highest Peak As Reference

I have data where I need to return the values that are low by keeping the highest value or peak as a reference, there are many peaks, I need to return the lows of each peak and sto

Solution 1:

The zip() function is very useful when you are looking for patterns of relative values within a list. It allows you to obtain pairings (or triples) of values that are next to each other.

deffindHighPeaks(A,count):
    # positions of values that are top of hills or bottom of valleys
    pivots   = [i for a,(i,b),c inzip(A,enumerate(A[1:],1),A[2:])
                                if a>b and b<c or a<b and b>c]

    # merge pivot positions into triples# representing the low-high-low or high-low-high indexes
    iWaves = [(left,mid,right) for left,mid,right
                               inzip([0]+pivots,pivots,pivots[1:]+[len(A)-1])]
    
    # extract only peak values from patterns of hills and valleys
    peaks  = [(A[left],A[mid],A[right]) for left,mid,right in iWaves
                                        if A[left]<A[mid]]

    # find the highest peaks, and put them in a set
    highPeaks = set(sorted(peaks,key=lambda p:p[1])[-count:])

    # Return high peaks, in original orderreturn [p for p in peaks if p in highPeaks]

# A = big list
    
Q,R,S = zip(*findHighPeaks(A,6)) # large exampleprint(R) # (7237, 7288, 7215, 7242, 7368, 7469) peaksprint(Q) # (6420, 6475, 6388, 6381, 6502, 6659) Low on the leftprint(S) # (6076, 6180, 6452, 6018, 6176, 6337) Low on the right

A = ['22','21','22','23','24','25','26','27','28','27','24','15','23',
   '22','32','30','28','20','27','17','22','28','42','40','35','22','16']

Q,R,S = zip(*findHighPeaks(A,3)) # small exampleprint(R) # ('28', '32', '42') peaksprint(Q) # ('21', '22', '17') Low on the leftprint(S) # ('15', '20', '16') Low on the right

Here is a visual representation of the selection process, which is based on relative variations (increasing/decreasing).

                                  HI                                        
                                 '28''27''27'      HI    HI                     HI   
                           '26''24''23''32''42''25''15''22''30'     HI      '28''40''24'                   LO    LO     '28''27''22''35''23''20''17''22''22''22'                                          LO    LO                  '16''21'
            LO

peaks:                           2823322742||-------------------^^-------||--^^-||-^^------||-^^-||-------^^----------||left:       2115222017right:                                    1522201716