How to calculate the means of n adjacent units of a vector?

Hi, i have a question about vectors.

For example i have a vector A=[1 2 3 4 5 6 7 8 9 10]T I want to get the mean values of every two adjacent units in this vector. I mean i should get B=[1,5 2,5 3,5 4,5 5,5 6,5 7,5 8,5 9,5]T

1,5=(1+2)/2 , 2,5=(2+3)/2 etc.

or every 3 units i should get: C=[2 3 4 5 6 7 8 9]T

2=(1+2+3)/3 , 3=(2+3+4)/3 etc.

or every 4 units i should get: D=[2,5 3,5 4,5 5,5 6,5 7,5 8,5]T etc.

Is there any way to do that for large vectors by using mean() function easily (not using any loop)?

Thanks in advance

Answer 1

[Roger Stafford]

If you want the mean of each n successive values in A, to place it in X, do this:

   X = mean(hankel(A(1:n),A(n,end)),1);

[Ekin]

Thanks for the answer, but this still gives a 1x1 vector.

[Guillaume]

There's a typo in Roger's answer (should be A(n:end)) but otherwise, it works exactly as you want:

cummean = @(V, n) mean(hankel(V(1:n), V(n:end)), 1);

A = [1 2 3 4 5 6 7 8 9 10]
D = cummean(A, 4)

returns:

D =
    2.5  3.5  4.5  5.5  6.5  7.5  8.5

[Roger Stafford]

Not if length(A) is greater than n. Set n = 2 and try it on your example for A = 1:10. You should get the B you described. Set n = 4 and get your D.

[Roger Stafford]

Oops, you're right, Guillaume. It should be

X = mean(hankel(A(1:n),A(n:end)),1);

[Ekin]

Oh, thanks. It works fine for now.