how to find max and min value within a certain range of a plot

Hi, I'm using plot function to identify second wave and measure it's frequency, so is there any way for me to get timeseries of the max and min value within the second wave range directly without have to search them in csv files. Thank you.

[Antoni Garcia-Herreros]

Do you havethe mat file?

[ZENONG]

This is the plot file and want to know how to find the timeseries of first upper peak and second lower peak.

Answer 1

[Star Strider]

Use the bounds function on the specific plot argument.

[Star Strider]

EDIT — (13 Apr 2023 at 17:34)

I am not certain what you want. This provides the peak values, locations, and frequencies of each peak, valley, and complete wave. (The frequencies are not printed on the plot because there is not room enough for them.)

I = openfig('tek0000ALL.fig');
grid

Lines = findobj(I, 'Type','line');
xv = Lines.XData;
yv = Lines.YData;
Tss = [mean(diff(xv)) std(diff(xv)) median(yv)];
Fs = 1/Tss(1);
[pks,plocs] = findpeaks(yv, 'MinPeakProminence',max(yv)/4);
[vys,vlocs] = findpeaks(-yv, 'MinPeakProminence',max(-yv)/4);

zxix = find(diff(sign(yv-median(yv))));
rtbl = find(zxix>max(vlocs),1,'first');
zxix = zxix(1:rtbl);
periodv = diff(xv(zxix));
pervbfr = buffer(periodv,2);
freqv = 1./sum(pervbfr)                         % Frequency Of Each Complete Wave

freqv = 1×4

1.0e+06 * 0.8039 2.8090 1.2136 0.5869

figure
plot(xv, yv)
hold on
hold off
grid
yline(median(yv))
text(xv(plocs), pks, compose(['(%.2fx10^{-5}, %.3f)'],[xv(plocs)*1E5; pks].') )
text(xv(vlocs), -vys, compose(['(%.2fx10^{-5}, %.3f)'],[xv(vlocs)*1E5; -vys].') )

.

[ZENONG]

Thank you!

[Star Strider]

As always, my pleasure!