How do I get the sum of the averages for a specific time step?
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I am using: mean_time = sum(mean(mean(mean(total)))); to get the sum of the averages of a 4D matrix. How do I change this to get the sum for a specific timestep? For example, if I wanted timestep 5 or 8 specifically rather than the sum of the entire thing (which is what the above does).
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Adam Danz
el 29 de Jun. de 2018
Editada: Adam Danz
el 29 de Jun. de 2018
In which of the 4 dimensions are the time steps?
When you calculate mean(total) you are taking the mean across the first dimension. So when you calculate mean(mean(total)), you are calculating the first dimension of the mean(total) array. To demonstrate that, see how the size of each dimension changes after each mean:
K>> size(total)
ans =
4 4 4 4
K>> size(mean(total))
ans =
1 4 4 4
K>> size(mean(mean(total)))
ans =
1 1 4 4
K>> size(mean(mean(mean(total))))
ans =
1 1 1 4
If you were to use squeeze() in each of the steps above you'd see the number of dimensions decrease at each step.
If you want to take the mean over a dimension other than the first, use the second input to mean(). To answer your question, it depends upon which dimension describes the time steps.
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Adam Danz
el 29 de Jun. de 2018
In your 4D array, if the 4th dim is time and you'd like to isolate all data from the 588th time step,
time588 = total(:,:,:,588);
which is now a 3D array of size
size(time588)
I'm not sure of your averaging methods but if you're executing
mean(mean(time588))
Then you're averaging across the 1st dimension, then averaging the averages across the 1st dimension again; all for data from time step 588.
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