MATLAB: 5 point asymmetric moving average using past values

Question

Hello everyone, and thank you in advance for taking the time to inspect my question.

I am currently working on a code that will allow me to take a signal and apply a 5-point asymmetric moving average filter (Past Values) to it. In an attempt to do that, I have written the following code:

N = length(ECG); %The number of rows in the columns of the ECG data: Both columns contain 1040 rows

A = ECG(:,2); %The second column of the ECG data specifies amplitude

time = ECG(:,1); %The first column of the ECG data specifies the time point

for i = 5 : (N) %Sets a counter

asym5p(i)= mean(A(i-4:i)); %Creates a vector from the mean of the four previous terms & the term of interest

end

plot (time (5 : (N)), asym5p, 'm') %Plots the vector with time on the x-axis and voltage on the y-axis

xlabel('Time (sec)');

ylabel('Amplitude (Volts)');

title('5 Point Asymmetric Filter (Future)');

Despite my best efforts, I cannot understand why the code will not compile, as I keep receiving the error message "Vectors must be the same length."

Any insight into this would be greatly appreciated.

Regards,

Luke Pretzie

Answer 1

Looks like when you are plotting, size of asym5p is 1x1040 while size of time (5 : (N)) is 1x1036. These need to be same length for plot to work. For e.g. if I change the following line

plot (time (5 : (N)), asym5p, 'm')

to the following line

plot (time , asym5p, 'm')

The code will work.

P.S: I generated ECG data as follows to run your code. For the future, consider attaching the data or provide the sample inputs for easy replication of code behavior.

ECG = rand(1040,2);