Calculate mean of every nth row in a table

Dear MATLAB experts,

I'm trying to get the mean value of every third row starting from the first row in a table. So, I would like to get the mean value of the 1st, 4th, 7th, 10th, 13th, 16th, 19th... up to the 666679th row and apply the same approach to the other remaining rows, 2nd, 5th, 8th, 11th, 14th... up to the 666680th row and to the 3rd, 6th, 12th, 15th, 18th... up to the 666681th row.

This means that I would like to get 3 mean values and I want to do this for the column of the table you will find attached to this post.

I would really appreciate your help since I don't even know how to approach this problem. Thank you in advance.

Answer 1

[André Kucharzewski]

>> v = randi(100,100,1)

>> mean(v(1:2:end)

or mean(v(1:3:end)

in your case end could be 666679

[chiefjia]

Shouldn't it be:

mean(v(1:3:end))

mean(v(2:3:end))

mean(v(3:3:end))?

[DGM]

Yes. That will take the means of three interleaved samplings of v.

Consider the example:

v = [1 2 3 1 2 3 1 2 3 1 2 3];

% samples
v1 = v(1:3:end)

v1 = 1×4

1 1 1 1

v2 = v(2:3:end)

v2 = 1×4

2 2 2 2

v3 = v(3:3:end)

v3 = 1×4

3 3 3 3

% means
mean(v1)

ans = 1

mean(v2)

ans = 2

mean(v3)

ans = 3

[chiefjia]

Perfect, thanks a lot!!