Find coordinates of border in findpeaks plot

Hi all,

I am struggling to find the cooridnates for the borders value while using the findpeaks function.

Here is a picture of my plot:

I would need to find the x coordinates of the borders between the peaks. I am doing so in order to get the duration of each peak delimited by the purble borders.

My code right now looks like this:

load('pO2,Mean,Numeric,Float,Raumedic,data_part1of1.mat');

ox = measurement_data;
smooth_ox = smooth(ox, 0.01, 'loess');

%find peaks
[pks,locs,wdths] = findpeaks(smooth_ox,'MinPeakProminence',0.5);
locmax = islocalmax(smooth_ox);

%plot
figure()
findpeaks(smooth_ox,'MinPeakProminence',0.5,'Annotate','extents',...
          'WidthReference','halfheight')
text(locs+.02,pks,num2str((1:numel(pks))'))
title('Peaks')

Thank you for the help!

Answer 1

[Star Strider]

Using an example from the findpeaks documentation —

x = linspace(0,1,1000);

Pos = [1 2 3 5 7 8]/10;
Hgt = [4 4 2 2 2 3];
Wdt = [3 8 4 3 4 6]/100;

Gauss = Hgt.'.*exp(-((x-Pos.')./Wdt.').^2);
smooth_ox = sum(Gauss);

%find peaks
[pks,locs,wdths] = findpeaks(smooth_ox,'MinPeakProminence',0.5);
locmax = islocalmax(smooth_ox);

%plot
figure
findpeaks(smooth_ox,'MinPeakProminence',0.5,'Annotate','extents',...
          'WidthReference','halfheight')
text(locs+.02,pks,num2str((1:numel(pks))'))
title('Peaks')

Ax = gca;                                               % Axes Handle
% GetAx = get(Ax)                                         % Explore ...
% GetAx.Children                                          % Explore ...
hlb = findobj(Ax,'Type','line', 'tag','Border')         % Handles Array To Linew Sith 'Border' Tag

hlb = 
  2×1 Line array:

  Line    (Border)
  Line    (Border)

hlb(1).XData                                            % Desired Result

ans = 1×12

146 146 NaN 419 419 NaN 587 587 NaN 1000 1000 NaN

hlb(2).XData                                            % Desired Result

ans = 1×12

1 1 NaN 146 146 NaN 419 419 NaN 587 587 NaN

It might be necessary to use a for loop to get all of them in your situation (data not provided), however it should be straightforward to get them using this approach:

for k = 1:numel(hlb)
    BorderX(k,:) = hlb(k).XData;
end

BorderX                                                 % View Result

BorderX = 2×12

146 146 NaN 419 419 NaN 587 587 NaN 1000 1000 NaN 1 1 NaN 146 146 NaN 419 419 NaN 587 587 NaN

Make appropriate changes to get the result you want.

.

[Luca de Freitas]

Thank you so mich for the help! Issue solved!

[Star Strider]

As alsays, my pleasure!

.