MATLAB: How to segment data using overlapping window

MATLABoverlapping_windowsegmentation

Hello, I have an ECG data of 20mins length (2×307200). I want to apply a 20 sec window(5120) with an overlap of 64samples. I want 20 sec segments so i can extract features from it. I tried to write a loop for window but it doesn't give me right answer. Can somebody help me.
ECG_data=[time; ECG];  
N_max=length(ECG_data);
  n_window=5120;
  overlap_win=64;
  count=1;
  for n_start = 1:overlap_win:(N_max-n_window)
      New_data(count,:) = ECG_data(n_start_1:(n_start+ n_window));
      do something..
     mean(count,:)=mean(new_data);
    count=count+1;
    end
The number of samples in each window is limited to 4720 sample(thats 18 sec) even though i need 20sec(5120). What am I doing wrong here? it something to do with the termination of window?? Also how can i retain the time information after applying window?

Best Answer

Something that's really not clear is that your ECG_data has two rows, yet within your loop you're using linear indexing, which is not consistent. The end result, when n_start is 1 is that New_data(1, :) is [time(1), ECG(1), time(2), ECG(2), ...].
Assuming you only want the second row (ECG) of ECG_data in new_data, a very simple way to create it in one go, without a loop is with:
Matlab R2016b or later only:
new_data = ECG((0:64:307200)' + (1:5120));
Any version of matlab:
new_data = ECG(bsxfun(@plus, (0:64:307200)', 1:5120));
You can do the same with time if needed
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