confusion during finding out the mean of a 3d vector
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SWARNENDU PAL
le 21 Juil 2021
Commenté : SWARNENDU PAL
le 21 Juil 2021
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.
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Chunru
le 21 Juil 2021
Modifié(e) : Chunru
le 21 Juil 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 commentaires
Bruno Luong
le 21 Juil 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'))
Plus de réponses (1)
Jonas
le 21 Juil 2021
the short answer:
your second approach takes mean values of means and the first approach takes the mean value of all elements
2 commentaires
Walter Roberson
le 21 Juil 2021
Those work out the same except when there are nan that are being omitted.
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