Leaping loop with constant rows for each identity

I have a vector where the first 80 rows belong to a company, the 2nd 80 to another company ... last 80 rows belong to company N I want a rolling average of the last 12 rows for all rows starting row 12. so for row 12, i want the average of rows 1 till 12, for row 13 i want the average of rows 2 till 13 ....for row 80 the average of rows 69 till 80. but for row 81 till 91 it should be empty since i don't have 12 observations that proceeds these rows.then it starts again row 92 is the average of rows 81 till 92 etc.... How can I design this till i reach the end of the vector? i tried

for i=12:80:N
A(i)=B(i:i-11,1);
end
but it doesn't work  properly. Any hint will be greatly appreciated

Answer 1

[Andrei Bobrov]

A - your array (n x 1)

out = conv2(A,ones(12,1)/12,'valid');