How to pick a set of data close to one another

I would like to automate the process of choosing the data series that are withing a range close to the overall data line (black line in figure). Is there a way to do this in MATLAB? Below is the picture of my 21 data series and I am only interested in the series that are close to it. The process I have to do to pick them out is trial-and-error, but I would like to develop a code that could find the series that are within 2 orders of magnitude at any given point of the overall. Any suggestions?

Answer 1

[dpb]

Is the reference fixed/known a priori, computed from the overall dataset...???

Presuming the former above and is xref, and other data is array x, the "deadahead" way would be something like:

dist=100;       % difference limit
[r,c]=size(x);  % I'll presume data are by column; transpose or flip logic if not
ix=false(c,1);  % none satisfied yet...just preallocated, will write in loop
for i=1:c
  d=abs(x(:,i)-xref);      % the point-by-point differences
  ix(i)=(min(d)<=dist);    % logical vector of those within
end
xsave=x(:,ix);             % save ones inside distance

Actually, it became clear it's easy enough w/o the loop, too...

d=abs(x-xref);  % relies on automagic vector expansion (I think this works, haven't learned all the nuances yet)
ix=any(d<=dist,1);
xsave=x(:,ix);