for loop not working

Hi, I have this signal and I want to find out the mean between the peaks. I know the x and y values at the peaks. this is my code

y1=locs+10; %wants few points before and after peaks to avoid mean being affected by the peak values thus +10

y2=locs-10; %locs is the y position of the peaks

for k= 1:length(locs)-1

ROI=transpose(y1(k):y2(k+1)); %transpose is the whole signal, trying to extract each region between peaks

mean2=mean(ROI);

end

The code works for one loop (i.e.k=1) but wont repeat it. But if I use 'ROI=transpose(y1(k):y2(k+1))' in the command window and physically type k=2 and 3 it will work. so I guess i'm missing a step in the for loop. any suggestions would be appreciated. Thanks in advance

Answer 1

[Star Strider]

We o not have your entire code. Note that the transpose call is not necessary, since the mean funciton also accepts a dimension argument, where 1 is down the rows for each column (the default) and 2 is across columns, taking the mean of each row.

[Aleena James]

it was giving me error without the transpose

[Star Strider]

Use the ‘dim’ argumnent in the mean function:

M = mean(A,dim)

as I already described. It should work then.

Try this demonstration code:

N = 100;
tv = linspace(0, 10, N);
signal = randn(1, N);

[pks,locs] = findpeaks(signal, 'MinPeakHeight',1, 'MinPeakDistance',5);

for k = 1:numel(locs)-1
    locv{k} = locs(k):locs(k+1);
    ROI(k) = mean(signal(locs(k):locs(k+1)), 2);
end

figure
plot(tv, signal)
hold on
plot(tv(locs), pks, 'vb')
for k = 1:numel(locv)
    plot(tv(locv{k}), ones(size(locv{k}))*ROI(k), '-k')
    text(median(tv(locv{k})), ROI(k), sprintf('\\mu = %.3f', ROI(k)), 'HorizontalAlignment','center', 'VerticalAlignment','bottom', 'FontSize',7)
end
hold off
grid

Make necessary changes to get the result you want.

[Aleena James]

thank you so much it works:)

[Star Strider]

As always, my pleasure!