How to index equally spaced chunks from a long signal?
    1 view (last 30 days)
  
       Show older comments
    
I have a long signal that includes 120 stimulation pulses evenly spaced. I have the indices of these pulses and I want to find the mean of the signal from 5-7 ms after each pulse to use as a baseline value. Currently, I am extracting individual pulses and able to find the mean of this time period from individual pulses, but how can I find the mean from all of them at once?
       for b = 1:numPulses
            windowBefore = round(0.001*db1.Fs);
            windowAfter = round(0.05*db1.Fs);
            window1 = -windowBefore:windowAfter;
            windowSelected = window1 + pulseIndexes(b);
            signal = db1.emg(windowSelected,d);
            m = mean(signal(ceil(Fs*0.005):ceil(Fs*0.007)))
0 Comments
Answers (2)
  David Hill
      
      
 on 14 Feb 2022
        
      Edited: David Hill
      
      
 on 14 Feb 2022
  
      ms5=1000;%approximate number of data samples after the pulse to start averaging on (should be based on your sample frequency)
ms7=1400;%approximate number of data samples after the pulse to stop averaging on (should be based on your sample frequency)
m=arrayfun(@(x)mean(yourData(indexOfPulses(x)+ms5:indexOfPulses(x)+ms7)),1:numel(indexOfPulses));
0 Comments
  Benjamin Thompson
      
 on 14 Feb 2022
        If you can define an index vector with ones in the positions where you want to calculate the mean, then you can use the index vector to pass a smaller subset of your data to the mean function.  For example, to get the mean of all samples exceeding 1 in a sinusoid of frequency 2, amplitude 2 ,for 5 seconds:
>> t = 0:0.01:5;
>> x = 2*sin(2*pi*2*t);
>> figure, plot(t, x)
>> Ipulse = x > 1;
>> mean(x(Ipulse))
ans =
    1.6808
>> 
0 Comments
See Also
Categories
				Find more on Matrix Indexing in Help Center and File Exchange
			
	Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!