Creating averages for parts of an array in a for loop

Hi,

I have 200 instances of data within an array and I would like to create a (mean) average using the last 5 instances of data for every data point.

The code I am currently using to manually do this is as follows:

a1=mean(a(1)); A1=a(1)-a1;

a2=mean(a(1:2)); A2=a(2)-a2;

a3=mean(a(1:3)); A3=a(3)-a3;

a4=mean(a(1:4)); A4=a(4)-a4;

a5=mean(a(1:5)); A5=a(5)-a5;

a6=mean(a(2:6)); A6=a(6)-a6;

a7=mean(a(3:7)); A7=a(7)-a7;

a8=mean(a(4:8)); A8=a(8)-a8;

a9=mean(a(5:9)); A9=a(9)-a9;

a10=mean(a(6:10)); A10=a(10)-a10;

Is there anyway I could use a for loop to drastically reduce the amount of code needed?

Thanks in advance,

Jack

[Stephen23]

"Is there anyway I could use a for loop to drastically reduce the amount of code needed?"

Using numbered variables is entirely the wrong way to go about this task.

Using numbered variables is a sign that you are doing something wrong, and are not taking advantage of MATLAB's strengths (processing arrays, indexing, etc.).

Copy-and-pasting code is also a sign that you are doing something wrong.

Answer 1

[Stephen23]

Your definitions of the boundary cases make this a bit tricky, but here is one solution:

>> A = randi(9,1,10)
A =
   3.00   2.00   2.00   2.00   3.00   6.00   8.00   1.00   8.00   2.00
>> F = @(n)mean(A(max(1,n-N+1):n));
>> M = arrayfun(F,1:numel(A))
M =
   3.00   2.50   2.33   2.25   2.40   3.00   4.20   4.00   5.20   5.00

You could also use conv , although you would need to handle the boundary cases yourself.

[Jack Upton]

Sorry this is the full code, with boundary cond.

X=csvread('NoiseX01s20s.csv');
t=X(:,1); %Time Values
g=X(:,2); %Acceleration Values
a=g*9.81; %convert to m/s^2
a1=mean(a(1));      A1=a(1)-a1;
a2=mean(a(1:2));    A2=a(2)-a2;
a3=mean(a(1:3));    A3=a(3)-a3;
a4=mean(a(1:4));    A4=a(4)-a4;
a5=mean(a(1:5));    A5=a(5)-a5;
a6=mean(a(2:6));    A6=a(6)-a6;
a7=mean(a(3:7));    A7=a(7)-a7;
a8=mean(a(4:8));    A8=a(8)-a8;
a9=mean(a(5:9));    A9=a(9)-a9;
a10=mean(a(6:10));  A10=a(10)-a10;

I have managed to calculate the moving average using the conv command, is there now a way to calculate the rate of change of conv?

[Stephen23]

"is there now a way to calculate the rate of change of conv"

It is not clear what "rate of change of conv" means. Perhaps you want diff.