How do I combined all peak to become one spectral line?

Hi guys, from the code I have I managed to produce the graph:

%get list of element, prompt user to select one, and get content of element file
filelist  = dir('*.txt');
[~, elementlist] = arrayfun(@(f) fileparts(f.name), filelist, 'UniformOutput', false);
[elementindex, ok] = listdlg('ListString', elementlist, 'PromptString', 'Select an element', 'SelectionMode', 'single');
if ~ok, return; end  %terminate if user click cancel
elementdata = importdata(filelist(elementindex).name);
assert(isnumeric(elementdata), 'Element does not have data');  %abort if the file does not contain a matrix
%build wavelength array
step = 0.02;
ss = 100;
steparray = -step*ss : step : step*ss;
new_wavelength = (elementdata(:, 1) + steparray);  %no loop needed. Requires R2016b or latter
%get row selection
[selectedrow, ok] = listdlg('ListString', compose('%f', elementdata(:, 1)), 'PromptString', 'Select a wavelength', 'SelectionMode', 'multiple');
if ~ok, return; end  %terminate if user click cancel
%build Peak vector for selected row
Delta_lambda = 0.2;
int_fact = elementdata(selectedrow, 2);
num = new_wavelength(selectedrow,ss+1)-new_wavelength(selectedrow,:);
denom = Delta_lambda/2;
Peak = (int_fact.*(1./(1+(num/denom).^2)));
%combined peak vector for selected row
plot(new_wavelength(selectedrow, :).', Peak.')

How do I combined all the peak that I chose to become as the graph below bcs I have try by using sum(peaks) but i doesnt work so im not sure how should I do it. One of the expert(Mathworks society) told me to resample each row to the same wavelength before i can sum it but im not sure how should i do it.

I have attached the element file as well. Thanks in advanced.

[jonas]

How did you even plot the three peaks at the same time? When I run the code I get one peak and, if I understand correcrtly, if I run the script again it overwrites the old peak. Did you just use 'hold on'?

Also, do the peaks share the same x-vector? That's important, because you will not be able to simply sum them up if they are not sampled at the same xvalues.

[Mohamad Khairul Ikhwan Zulkarnain]

I got more than one peak at the same time bcs when i select the number of row for wavelength, i select more than one row which eventually will create more than one peak at a time. I dont think my peak share the same x-vector since each peak has its own row but as you see in the first picture, there are some part of the peak is overlapping. Cant we just sum it up? If not, what should I do to sum it up? Can you show it to me?

[Guillaume]

For info, (a bit late), this is a continuation of why-am-i-getting-an-error-of-subscripted-assignment-dimension-mismatch

Answer 1

[jonas]

They key is to resample the curves along a common x-vector. You can do this by interp1. Just add these new lines of code:

% ... old code
Peak = (int_fact.*(1./(1+(num/denom).^2)));

% ...New code begins here
x=new_wavelength(selectedrow,:);
y=Peak;

% Remove rows with NaNs
x(isnan(y(:,1)),:)=[];
y(isnan(y(:,1)),:)=[];

% Number of peaks
np=size(y,1); 

% New xvec
xh=min(x(:)):1e-3:max(x(:)); %new x vector

% Preallocate new peak vector
yh=nan(size(x,1),size(xh,2)); 

%Interpolate one peak at a time
for i=1:np
  yh(i,:)=interp1(x(i,:),y(i,:),xh);
end

% Sum column-wise, exclude nans
ysum=nansum(yh,1);

% Plot
plot(xh,ysum)

First three wavelengths of Ferum:

[Mohamad Khairul Ikhwan Zulkarnain]

Thanks Jonas. I just want to ask, is it only possible for three peak? What if I want to do all peak? Because I try to do all peak for copper excluding NaN but there is no graph coming out and ysum is all NaN. Why is that?

[jonas]

I will update the code. Should work for any number of peaks in a few minutes.

[Mohamad Khairul Ikhwan Zulkarnain]

Thank you so much!

[jonas]

No problem! Should work now.

[Mohamad Khairul Ikhwan Zulkarnain]

Thank you! You're lifesaver!