How to extract only first peak of each pulse (positive or negative) in sequence throughout the signal

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MANINDER CHOUDHARY
MANINDER CHOUDHARY 2022-5-25
评论： Voss 2022-5-27
I would like to extract only first value of the peak, whether its positive or negative in a sequence and store in a array
My code is
data = C;
t = 1:length(data);
figure
plot(t,data)
xlabel('original data');
ylabel('amp')
legend('Noisy data Signal')
grid on
[p,s,mu] = polyfit((1:numel(data))',data,1);
fn = polyval(p,(1:numel(data))',[],mu);
x_data = data - fn;
[~,locs_Rwave] = findpeaks(x_data,'MinPeakHeight',0.005,'MinPeakDistance',3000);
inv = -x_data;[~,locs_Swave] = findpeaks(inv,'MinPeakHeight',0.005,'MinPeakDistance',3000);
[m_Peak, locs_m_peak] = findpeaks(abs(x_data),'MinPeakHeight',0.005,'MinPeakDistance',3000);
pos_pulses= [x_data(locs_Rwave),locs_Rwave];
neg_pulses= [x_data(locs_Swave),locs_Swave];

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Voss
Voss 2022-5-25
Ran in:
load Example.mat
data = C;
t = 1:length(data);
[p,s,mu] = polyfit((1:numel(data))',data,1);
fn = polyval(p,(1:numel(data))',[],mu);
x_data = data - fn;
[pks_Rwave,locs_Rwave] = findpeaks(x_data,'MinPeakHeight',0.005,'MinPeakDistance',3000);
[pks_Swave,locs_Swave] = findpeaks(-x_data,'MinPeakHeight',0.005,'MinPeakDistance',3000);
[peak_locations,sort_idx] = sort([locs_Rwave; locs_Swave]);
peak_values = [pks_Rwave; -pks_Swave];
peak_values = peak_values(sort_idx);
plot(x_data)
hold on
plot(peak_locations,peak_values,'ro')
xlim([2.992e5 2.996e5])
first_peak_location = peak_locations(1)
first_peak_location = 299266
first_peak_value = peak_values(1)
first_peak_value = -0.0122
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MANINDER CHOUDHARY
MANINDER CHOUDHARY 2022-5-27
There are two peaks i.e. positive and negative however the pulse starts with negative peak value (First peak), i just want to take first peak value and store it somwewhere, and then move ahead to second pulse and repeat the same procedure trhrougout . Hope now its clear
Voss
Voss 2022-5-27
I think I understand now. You want to know the location and/or value of the first peak of each pulse, under the assumption that each pulse has two peaks.
The code I showed has all the peak locations sorted, so, since each pulse has two peaks and you want the first peak of each pulse, you can simply take every alternate peak, starting with the first peak:
peak_locations(1:2:end) % location of the first peak of each pulse
peak_values(1:2:end) % value or height of the first peak of each pulse

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