mean for matrix array

I have a matrix t_u(361,361,36) i want to calculate the mean for 6 files in a row.. the resulting matrix should look like 361*361*6

for i = 1 : 6 :36
    t_uavg(:,:,ceil(i / 6)) = mean(t_u(:,:,i : i + 5),3);
end

Is there any error in this code, it looks its working fine, the result is 361*361*6 but when i am plotting its not showing up anything for (:,:,4),(:,:,5) and (:,:,6)

Answer 1

[the cyclist]

I'm guessing the issue is with your t_u array. This code ...

t_u = rand(361,361,36);
t_uavg = zeros(361,361,6);
for i = 1 : 6 : 36
    t_uavg(:,:,ceil(i / 6)) = mean(t_u(:,:,i : i + 5),3);
end
any(t_uavg(:)==0)

does not end up with any zeros in t_uavg, so I think your loop is right.

Answer 2

[Chad Greene]

I tested your code with t_u = rand(361,361,36) and it seems to give values for all 6 slices. Do you have some NaNs in t_u that might be screwing up the mean?

Two notes that are unrelated to your problem:

1. Try to avoid using i or j as variables. Matlab thinks i = sqrt(-1) unless you overwrite it. It's usually not an issue, but debugging can be a headache when you try to use i without defining it.

2. Before the loop, always preallocate. This can be a big issue for large datasets. Preallocate by putting this before the loop:

t_uavg = NaN(361,361,6);