# Is there a better way to solve this multidimensional array?

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Bianka Markovic on 11 Jun 2021
Commented: Bianka Markovic on 14 Jun 2021
Hello to everyone,
I'm currently trying to calculate annual temperatures and temperature anomalies. The data is given in one variable (here the M variable). It entails the temperatures for different longitude and latitude (basically temperatures on a regular grid), different depth and time. The first entry is the longitude and the second the latitude. The third one is for the different depth and the forth the time. The time represents 24 years, 12 entries per year meaning one temperature value for each month of the year.
The first loop is working fine even thou it takes some time. But the second loop takes too much time and effort that it never got through before my laptop broke down.
Does anyone knows maybe why it is not working, or has anyone a suggestion how could I make the program more efficient?
Thank you!
M=rand(1920,374,6,288);
sizetemp=size(M);
temp_mean=[];
for i=1:sizetemp(1); %longitude
for j=1:sizetemp(2); %latitude
for k=1:sizetemp(3) %depth
temp_mean(i,j,k)=mean(M(i,j,k,:));
end
end
end
m=1;
temp_annual=[];
an_temp=[];
for i=1:sizetemp(1); %longitude
for j=1:sizetemp(2); %latitude
for k=1:sizetemp(3) %depth
for l=1:12:sizetemp(4);
temp_annual(i,j,k,m)=mean(M(i,j,k,l:l+11));
an_temp(i,j,k,m)=temp_mean(i,j,k)-temp_annual(i,j,k,m);
m=m+1;
end
end
end
end

SALAH ALRABEEI on 11 Jun 2021
For the first averaging
%
temp_mean = nanmean(M,4);
For the 2nd annual avg use
%
A=reshape(M,19,3,6,size(M,4)/12,12);
an_temp = nanmean(A,5);
##### 1 CommentShowHide None
Bianka Markovic on 14 Jun 2021
Thank you for your answer Salah Alrabeei,
unfortunately the program shows an error:
Error using reshape
To RESHAPE the number of elements must not change.
Error in test (line 44)
A=reshape(M,19,3,6,size(M,4)/12,12 );

### More Answers (1)

Sulaymon Eshkabilov on 11 Jun 2021
Use mean2() intead of mean() that will help you to get rid of all loops.
##### 1 CommentShowHide None
Bianka Markovic on 14 Jun 2021
Its still taking too long to process :(

R2019a

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