## How can I do the average between many vector columns?

on 16 Apr 2014
Latest activity Commented on by Azzi Abdelmalek

on 17 Apr 2014

### José-Luis (view profile)

I have 120 1x500 vector columns, so I can't do it manually. For example, I have the following vector columns, each 1x500 in size:
a1, a2, ......, an, where n=120
I want to do:
(a1 + a2 + ... + an)/n
Thank you very much!

### José-Luis (view profile)

on 16 Apr 2014
Edited by José-Luis

### José-Luis (view profile)

on 16 Apr 2014

%Creating vectors:
for ii = 1:50
str = ['a' num2str(ii)];
assignin('base',str,rand(100,1));
end
%Preallocating:
your_mat = ones(100,50);
%Putting everything together, this is the part you want if you already have the vectors
for ii = 1:50
str = ['a' num2str(ii)];
your_mat(:,ii) = evalin('base',str);
end
your_val = mean(your_mat(:));

on 17 Apr 2014
Thank you for your answer. But the thing is that it gives me just a number, because that's what 'mean' function does, it gives a single number. When I average my 120 500x1 column vectors, namely (a1 + a2 + ... + an)/n, where n=120, it should give me a 500x1 vector column, not a single number.
If you could help further, that would be great! Thanks
lvn

### lvn (view profile)

on 17 Apr 2014
Replace the last line of Jose-Luis code with
your_val = mean(your_mat);
Then you will have what you want. However, much better would be to initially read in/or store your data in a matrix, rather than in separate vectors, then you can simply use what Azzi wrote.

on 16 Apr 2014

mean(A)

Azzi Abdelmalek

on 17 Apr 2014
You can use
mean(A,2)