Help saving the output of a for loop within a function into a vector.

Hello. I am currently writing the below function:

function [numout, outvec]= SCAN_DATA(vectin, lowlim, uplim)

%Compares each element of vectin against lowlim and uplim and returns 

%a count (numout) of how many vector elements are greater than or less than the 

%limits and a vector (outvec) of the actual out-of-limit readings

for k=1:length(vectin)

      if vectin(k)>lowlim && vectin(k)<uplim;

         outvec=vectin(k)

         numout=numel(outvec)

      else outvec=0

      end

end

I would like to save the data output into the vector named vectin but I only get the last output run through the loop. I am pretty new to this after looking around online, I can't figure it out. Can anyone help?

Answer 1

[James Tursa]

There are vectorized ways to do this (without a loop), but to answer your question directly you could add the index numout onto your outvec "storage" line. E.g.,

numout = 0;
outvec = [];
for k=1:length(vectin)
      if vectin(k)>lowlim && vectin(k)<uplim;
         numout = numout + 1;
         outvec(numout) = vectin(k);
      end
end

This assumes the "out-of-limit" readings are the ones between the limits as you have it originally coded. If the "out-of-limit" readings are the opposite, then you need to fix the if-test.

Vectorized methods can avoid the loop, and avoid incrementally increasing the size of a variable (outvec in this case) inside a loop. E.g., you might explore what you get with these two statements and then think about how to combine them in a vector sense to get your answer directly from them:

% With no indexes used, these two expressions return vectors
vectin > lowlim
vectin < uplim

[Matt Leis]

That did it. Thank you!

[James Tursa]

How are you calling the function? To get the variables in the workspace make sure you are capturing two outputs. E.g., call it like this:

[numout, outvec] = SCAN_DATA(vectin, lowlim, uplim);

Answer 2

[Andrei Bobrov]

l0 = vectin>lowlim & vectin<uplim;
outvec = l0*vectin;
numout = nnz(l0);