How can i find cumulative mean inside a for loop?

Hey everyone,

I have a code which helps me to calculate the mean values. Each of the "cellList.meshData(j)" corresponds to a single column vector of values. I would like it to give me the total mean of all 25 cells. The following code gives me the mean for each cell.

for j=1:25
    data=cellList.meshData(j);
    if isempty(data{1,1})
        continue
    end
mean_int_val = mean(cellList.meshData{j}{1,1}.signal2);
end

[Johannes Fischer]

To imporve code-readability, I would not use 'continue' in this case:

for j = 1:25
    data = cellList.meshData(j);
    if ~isempty(data{1, 1})
        mean_int_val = mean(cellList.meshData{j}{1, 1}.signal2);
    end
end

Answer 1

[Nicolas B.]

Hi,

For your situation, you should consider that . So they are 2 situations:

1. All vectors have the same size
2. Vectors can have different sizes

If you are in the first situation, I would simply keep all mean_int_val and simply recompute the the mean of all means.

nData = 25;
mean_int_val = NaN(1, nData);
for j=1:nData
    data=cellList.meshData(j);
    if isempty(data{1,1})
        continue
    end
    mean_int_val(j) = mean(cellList.meshData{j}{1,1}.signal2);
end
mean_total = mean(mean_int_val, 'omitnan');

If you are in the second situation, I would also keem the number of samples and then compute the mean.

nData = 25;
mean_int_val = NaN(1, nData);
mean_size    = NaN(1, nData);
for j=1:nData
    data=cellList.meshData(j);
    if isempty(data{1,1})
        continue
    end
    mean_int_val(j) = mean(cellList.meshData{j}{1,1}.signal2);
    mean_size(j)    = numel(cellList.meshData{j}{1,1}.signal2);
end
mean_total = sum(mean_int_val .* mean_size) / sum(mean_size);

[Meghana Balasubramanian]

Hey, Nicolas Broch, in the solution for the second stuation, did you mean mean_int_val(j) instead of mean_int_val(i)?

[Meghana Balasubramanian]

This isn't the answer I was looking for. Maybe my question wasn't very clear, I apologize for that.

I would like my final output to be the mean of all 25 mean values. Your solution just gives me the individual mean values of the 25 cells.

[Nicolas B.]

Thanks for the comment. I corrected it with j instead of i (bad habits).

In my suggestions, the mean of all means is saved in mean_total variable.

[Meghana Balasubramanian]

Yes, I just tried the first solution out. It works for my purposes.

Thank you! :)