MATLAB: How to shorten the code to prevent writing the same thing over and over

simplify code

code I am using is as follows:
for i=1:length(Rpeaks) %starts at first peak which is first whole step
    %if i==1
    if Rpeaks(i)-halfsegment<0
        window=(1:Rpeaks(i)+halfsegment); %takes into account that the forces don't start a full halfsegment prior to first valley
        step=GRFright(window); %assign the step the actual data values


        normstep=(step./max(step)); %normalize the step


        toeoff=find(normstep < min(normstep)+.05 , 1);
        RTO(n)=toeoff+window(1);
        heelstrike=find(normstep(toeoff:end) > min(normstep)+.05 , 1);% 1st zero location; syntax of ,1 returns first satisfying value


        RHS(n)=heelstrike+toeoff+window(1);
    elseif Rpeaks(i)+halfsegment>length(GRFright)
        window=(Rpeaks(i)-halfsegment:size(GRFright));
        step=GRFright(window); %assign the step the actual data values
        normstep=(step./max(step)); %normalize the step
        toeoff=find(normstep < min(normstep)+.05 , 1);
        RTO(n)=toeoff+window(1);
        heelstrike=find(normstep(toeoff:end) > min(normstep)+.05 , 1);% 1st zero location; syntax of ,1 returns first satisfying value
        RHS(n)=heelstrike+toeoff+window(1);
    else
        window=(Rpeaks(i)-halfsegment:Rpeaks(i)+halfsegment); %find window of frames-100 added to catch full end of step
        step=GRFright(window); %assign the step the actual data values
        normstep=(step./max(step)); %normalize the step
        toeoff=find(normstep < min(normstep)+.05 , 1);
        RTO(n)=toeoff+window(1);
        heelstrike=find(normstep(toeoff:end) > min(normstep)+.05 , 1);% 1st zero location; syntax of ,1 returns first satisfying value
        RHS(n)=heelstrike+toeoff+window(1);
        n=n+1;
    end
end
within the for loop I have the same lines written three times after the "If statement" defining what the window should be. Is there a way to shorten the code so I only have to make one change for each condition when necessary? Thanks in advance.

Best Answer

if Rpeaks(i)-halfsegment<0
  window=(1:Rpeaks(i)+halfsegment); %takes into account that the forces don't start a full halfsegment prior to first valley
elseif Rpeaks(i)+halfsegment>length(GRFright)
  window=(Rpeaks(i)-halfsegment:size(GRFright));
else
  window=(Rpeaks(i)-halfsegment:Rpeaks(i)+halfsegment); %find window of frames-100 added to catch full end of step
end
step=GRFright(window); %assign the step the actual data values
normstep=(step./max(step)); %normalize the step
toeoff=find(normstep < min(normstep)+.05 , 1);
RTO(n)=toeoff+window(1);
heelstrike=find(normstep(toeoff:end) > min(normstep)+.05 , 1);% 1st zero location; syntax of ,1 returns first satisfying value
RHS(n)=heelstrike+toeoff+window(1);
n=n+1
The above presumes that the increment on n is missing inside the first two conditions; if not, you're overwriting the arrays until the else case is selected so might as well throw them away, anyway.
Might be more legible if used select case end construct rather than the if elseif else end but that's also somewhat in the eye of the beholder.
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