looping through columns of a matrix and saving output

I have a matrix which is 1000x4. Each column is a different experiment run.

I want to loop through each column of the matrix and reshape it by taking the mean of every 1000 values.

for a = 1:4;
GTsec = mean(reshape(vel(1:1000),10,[]),1); %reshape to per second by taking the mean GT over 1000 files
end 

[Willie Smit]

What is the size of vel?

It is not clear from the code, but it seems like you want to calculate the mean, standard deviation, minimum and maximum for different experiments. If each column of vel stores the data of one experiment, then the commands

mean_GT=mean(vel);
std_GT=std(vel);

will return row vectors, where each entry corresponds to an experiment.

[C.G.]

ok I understand, thanks. I said vel is a 1000x4 double; 4 columns, 1000 entries.

The main thing I want to do is I want to reshape each column and create a new matrix of the reshaped data.

I can do one column of this using the code below but every time it overwrites the previous and I dont want it to.

GTsec = mean(reshape(vel(1:1000),10,[]),1); 

Answer 1

[KSSV]

This kind of error occurs when you are trying to save more number of elements than it is intiliazed.

Example:

A = zeros(1,3) ; 
A(1) = rand ;  % no error, becuase you are saving one element as initilaized 
A(2) = rand(1,2) ; % error becuase you are saving two elements instead of one 

Unable to perform assignment because the left and right sides have a different number of elements.

So you are trying to save RHS which has multiple elements into LHS which is initialized as a single element. To avoid the error, get the dimensions in prior and initialize properly and save. If not save them into a cell array.

A = cell(1,2) ;
A{1} = rand ;
A{2} = ran(1,3) ; 

[C.G.]

Ok I understand the error, thank you.

I am trying to reshape each column and create a new matrix of the reshaped data.

I can do one column of this using the code below but every time it overwrites the previous and I dont want it to, thats why I was trying to use a loop and this is the line it errors on.

GTsec = mean(reshape(vel(1:1000),10,[]),1);