How do I get a maximum and minimum for a singular wave while ignoring the other local maximums and minimums?

I have wave data from a buoy and am trying to identify the overall crest and trough amplitude for 50 individual waves. However, when using islocalmax/min it identifies all the locals and not the highest absolute value. I tried using minprominence but the amount of data points for each crest and trough is inconsistent. The section of code I'm using is below(original data file is .dat extension so I converted to .txt to upload here).

filedata=load('waves_n_130.dat');

A= filedata(:,4);

for n=1:8191

wmin=islocalmin(A,'MinProminence',0);

wmax=islocalmax(A,'MinProminence',0);

end

Answer 1

[Star Strider]

Using my code in How can I create isolated waves from data I have? —

LvPks = islocalmax(y, 'MinProminence',0.01, 'MinSeparation',45); % 'islocalmax'

plocs = find(LvPks);

pks = y(plocs);

[maxpk,ploc] = max(pks)

This returned:

maxpk = 0.2899

ploc = 79

and:

[mintr,tloc] = min(trs)

returned:

mintr = -0.3222

tloc = 77

And this:

Pk_Tr_Amp = pks(1:end-1)-trs;

[maxamp,loc] = max(Pk_Tr_Amp)

returned:

maxamp = 0.5668

loc = 77

Just add those lines (and perhaps others) to my code to get the results you want.

NOTE — There is one more peak than trough, and the vector lengths must be equal in order to compare them.

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