Plotting reflectance against time

I have plotted reflectance against wavelength using the following code, but now wish to plot reflectance against time. I have 2400 files each containing a complete spectrum at a certain point in time. There is 0.5 secs between each spectrum being recorded. I wish for the reflectance (2nd column) to be averaged for each spectrum

dirname='E:\Blue Wool Reflectance\';
head=[dirname 'BW Reflectance00000' '.txt'];
A=load(head);
wv=A(:,1);
R0=A(:,2);
mean(R0(200:1400))
timedifference=0.5
R=zeros(2048,2400);             
for i=1:9
   head=[dirname 'BW Reflectance0000' num2str(i) '.txt']; 
   A=load(head);
   R(:,i)=A(:,2);
end
for i=10:99
   head=[dirname 'BW Reflectance000' num2str(i) '.txt'];    
   A=load(head);
   R(:,i)=A(:,2);
end
for i=100:999
   head=[dirname 'BW Reflectance00' num2str(i) '.txt'];    
   A=load(head);
   R(:,i)=A(:,2);
end
for i=1000:2400
   head=[dirname 'BW Reflectance0' num2str(i) '.txt'];    
   A=load(head);
   R(:,i)=A(:,2);
end
i=200; 
figure(1)                   
plot(wv,R(:,i),'r')
xlim([400 700])
xlabel('\lambda')
ylabel('Reflectance%')

Answer 1

[Image Analyst]

If you load it into a 2-D array, R, where each row is a spectrum taken at some time, then you're going to have to have another array, acquisitionTimes, that contains the time each spectrum/row was taken at. Then you can pick a particular wavelength and plot it vs. times, something like

wavelength = 15; % Let's look at the wavelength in column 15 over time.
plot(acquisitionTimes, R(:, wavelength), 'b-', 'LineWidth', 2);
grid on;
xlabel('Time', 'FontSize', 20);
caption = sprintf('Reflectance at wavelength %d', wavelength);
ylabel(caption, 'FontSize', 20);

Answer 2

[Geoff Hayes]

Adam - in the future, please format your code so that it is readable. I have done this for you, but all you need to do is to highlight the code and press the {}Code button.

So presumably your above code shows that every column of R is the reflectance for a particular spectrum. To calculate the average, use mean as

 avgR = mean(R);

which you can then plot against time (which I don't think is the wv wavelength from above).

[Adam Woolsey]

Thanks for the tip. First time poster will remember for future.

My issue is how to create an array of time values that corresponds to each of the spectrums I recorded so that the mean from each spectrum is plotted against the time the spectrum was recorded. This information is not contained within the data so must be entered 'manually'