Save marked point on plot

Hello,

I would like to save the the x and y values of the marked point on the plot.

Can someone explain me please how to write a code or what functions can i use.

Thank you !

Answer 1

[Scott MacKenzie]

OK, this seems to to work. The x-y coordinates of the marked points are output to the command window (along with the figure number). For brevity, I'm just showing the result for the 1st data set.

format shortg
xlsdata=xlsread('temp.xlsx'); % this is the data in your ForDataMining.xlsx file
Wavelength=xlsdata(2:2152);

for i=1:1 % first data set only, adjust as desired
    reflection = xlsdata(2:2152,i+1);
    lmin = islocalmin(reflection,"MinProminence",0.01,"MinSeparation",100);
    
    % get x-y coordinates of minima
    x = Wavelength(lmin)';
    y = reflection(lmin);
    figNumber = repmat(i, numel(x), 1);
    [figNumber x y] % output in command window (include figure number)
    
    figure(i) % put figure statement here
    plot(Wavelength,reflection,Wavelength(lmin),reflection(lmin),'ro')
    title('Relative Reflectance-Wavelength')
    xlabel('Wavelength[nm]')
    ylabel('Relative Reflectance')
    grid on
    grid minor
end

ans = 7×3

1.0e+00 * 1 447 0.83857 1 1435 0.90312 1 1754 0.97845 1 1928 0.75198 1 2157 0.94879 1 2339 0.55042 1 2482 0.9139

[Anton Vernytsky]

Thank you for your help.

[Scott MacKenzie]

@Anton Vernytsky you're welcome. Glad to help.

Answer 2

[Scott MacKenzie]

Since you haven't provided any data or code, this is a rough answer only:

[pks, locn] = findpeaks(-y, 'MinPeakProminence', 0.1);

Using -y will give you the valleys, which is what you are after. You'll need to play with the peak prominence value to the get the valleys you want and exclude those you don't want. Then, you need to take the negative of pks to get the actual y values of the valleys. You can use locn to retrieve the corresponding x values.

[Anton Vernytsky]

Oh sorry,i wrote a code that finds this red point,what i did till now is to click on that point and right click and save data,i would like to write a code that save this point data auto.

This is my code:

clear all;
clc;
xlsdata=xlsread('ForDataMining.xlsx');
Wavelength=xlsdata(2:2152);
for i=1:10
reflection = xlsdata(2:2152,i+1);
lmin = islocalmin(reflection,"MinProminence",0.01,"MinSeparation",100);
plot(Wavelength,reflection,Wavelength(lmin),reflection(lmin),'ro')
title('Relative Reflectance-Wavelength')
xlabel('Wavelength[nm]')
ylabel('Relative Reflectance')
grid on
grid minor
figure(i)
end

[Scott MacKenzie]

Could you also post the data file? Just click on the paperclick and select the file.

[Anton Vernytsky]

Yes sure

[Scott MacKenzie]

OK,thanks. I posted a solution as a separate answer.