confusion during finding out the mean of a 3d vector
2 views (last 30 days)
Show older comments
I have a 3d vector of size 1498x1498x24. I want to calculate the wholes mean of the vector. I have used two method and got two different result. If anyone please explain this part that will be really helpful. I am giving the code and corresponding result.
mean(mmr_timeseries,'all','omitnan')
Using this i got the value 970.8025. Then i used :
mean(mean(mean(mmr_timeseries,'omitnan'),'omitnan'),'omitnan')
In this case I got 884.2371. I think these two lines are equivalent but I got different result. If ant=yone could please explain this part that will be really helpful. Thank you.
3 Comments
Accepted Answer
Chunru
on 21 Jul 2021
Edited: Chunru
on 21 Jul 2021
A 2-d example (applicable to 3d in principle).
a=[1 2; 3 3; nan 4; nan nan]
% mean of [1 2 3 3 4] after omitting nans
mean(a,'all','omitnan')
% mean for each column (omit nans)
mean(a,'omitnan')
% mean of the above vector , i.e. [2, 3]
mean(mean(a,'omitnan'),'omitnan')
% The following is for 3d (not shown in this example)
mean(mean(mean(a,'omitnan'),'omitnan'),'omitnan')
5 Comments
Bruno Luong
on 21 Jul 2021
. Then which one should be used?
A=[0 1; NaN 1; NaN 1; NaN 1; NaN 1; NaN 1; NaN 1; NaN 1; NaN 1]
mean(mean(A,'omitnan'),'omitnan')
mean(mean(A,'all','omitnan'))
More Answers (1)
Jonas
on 21 Jul 2021
the short answer:
your second approach takes mean values of means and the first approach takes the mean value of all elements
2 Comments
Walter Roberson
on 21 Jul 2021
Those work out the same except when there are nan that are being omitted.
See Also
Categories
Find more on Logical in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!